JPH06324274A - Scanning optics - Google Patents

Abstract

(57) [Abstract] [Purpose] Space saving and cost reduction by having common optical components in the reading optical system and the writing optical system while having both image information reading function and image writing function. It is to provide a scanning optical system capable of achieving the above. A writing optical system for scanning a writing scanning surface with a light beam modulated according to writing information and a writing optical system for writing an image on the scanning surface, and a reading scanning surface with a light beam for scanning the reading scanning surface. A reading optical system for reading image information on the basis of the reflected light from the optical path of the writing optical system and the reading optical system, and at least 1
The feature is that two optical elements are shared.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical system capable of performing optical scanning by deflecting a light beam using a deflecting mirror such as a polygon mirror as a light deflecting means.

[0002]

2. Description of the Related Art Conventionally, as a reading optical system, for example, a surface to be scanned is illuminated with a fluorescent lamp or the like, and the reflected light is reduced.
A projection lens is used to lead to a line sensor such as a CCD, and the detection output from this line sensor obtains image information for each line of the surface to be scanned, and at the same time, the surface to be scanned is orthogonal to the reading line. There is known an optical system that can obtain image information of the entire surface to be scanned by moving it.

Further, as a writing optical system, a polygon mirror is used to axially scan (main scan) the photosensitive layer on the surface of the photosensitive drum with a laser beam, and at the same time, the photosensitive drum is rotated (sub-scanning) to scan the surface of the photosensitive drum. An optical system for forming a latent image on a photosensitive layer is known. The latent image formed by this writing optical system uses a so-called electrophotographic method to form a toner image by developing toner (development), and the transfer device transfers the toner image onto recording paper. Then, the toner image transferred by the fixing device is fixed on the recording paper.

[0004]

However, in an apparatus that requires both a function of reading image information and a function of writing an image, such as a facsimile apparatus or a digital copying machine, the above-mentioned image information reading function is used. 2 reduction projection optical system and laser scanning optical system for writing
Two different optical systems must be provided, and improvements have been demanded from the viewpoint of space saving and cost reduction.

The present invention has been made in view of the above circumstances, and a main object of the present invention is to have an image information reading function and an image writing function, and to provide an optical component in a reading optical system and a writing optical system. A common purpose is to provide a scanning optical system capable of saving space and reducing costs.

Another object of the present invention is to provide a scanning optical system for reading image information and a scanning optical system for writing an image, which can be independently operated, and can operate these simultaneously. It is to provide a system.

Another object of the present invention is to save space by sharing the optical paths of a plurality of light beams, and to separate a plurality of light beams without substantially attenuating the light quantity. A scanning optical system capable of

[0008]

In order to solve the above-mentioned problems and to achieve the object, a scanning optical system according to the present invention, according to claim 1, modulates a writing scanning surface according to image information. The writing optical system for writing an image on this scanning surface by scanning with the scanned light beam and the scanning light beam on the reading scanning surface, and the image based on the reflected light from this scanned surface (reading scanning surface) A reading optical system for reading information is provided, and an optical path of the writing optical system and the reading optical system and at least one optical element are shared.

According to the eighteenth aspect of the present invention, the scanning optical system according to the present invention scans the writing scanning surface with the light beam modulated according to the writing information and writes an image on the scanning surface. Writing optical system and a reading optical system for scanning the reading scanning surface with a light beam and reading image information based on the reflected light from the scanning surface, and the optical paths of the writing optical system and the reading optical system. Is commonly provided in a switchable state, and at least one optical element is commonly provided in both optical systems.

According to a twenty-ninth aspect of the invention, the scanning optical system according to the present invention scans the writing scanning surface with the light beam modulated according to the writing information, and performs writing for writing an image on the scanning surface. An optical system and a reading optical system for scanning the reading scanning surface with a light beam and reading image information based on the reflected light from the scanning surface are provided, and the optical path of the writing optical system and the optical path of the reading optical system. Are provided independently of each other, and at least one optical element is commonly provided in both optical systems.

According to a thirty-ninth aspect of the present invention, in the scanning optical system, the writing scanning surface is scanned with the light beam modulated according to the writing information, and the writing is performed to write the image on the scanning surface. The optical system and scanning surface are illuminated with a light source that emits light having multiple wavelengths, the position corresponding to the light receiving element is scanned, and the reading is performed to read image information based on the reflected light from this scanning surface. An optical system is provided, and the optical paths of the writing optical system and the reading optical system and at least one optical element are shared.

According to a forty-third aspect of the invention, the scanning optical system according to the present invention further comprises: a light source for irradiating a light beam; Deflection means for deflecting the reflected light from the reading and scanning surface toward the light source, a light beam disposed in the optical path between the light source and the deflecting means, output from the light source, and the reflected light. And a beam splitter that spatially separates the.

Further, the scanning optical system according to the present invention is
According to the forty-seventh aspect, a light source for irradiating a light beam, a deflection unit for deflecting the light beam output from the light source for scanning the light beam on the reading scanning surface, and a reflected light from the reading scanning surface are received. A light receiving unit, a lens arranged between the reading scanning surface and the light receiving unit, for converging the reflected light, and having an optical axis of a light beam incident on the reading scanning surface and an optical axis of a light receiving system. The lens and the light receiving element are arranged so as to be different in a direction perpendicular to a scanning direction of a light beam incident on the reading scanning surface.

According to a forty-eighth aspect of the invention, the scanning optical system according to the invention scans the writing scanning surface with the light beam modulated according to the writing information, and writes the image on the scanning surface. An optical system and a reading optical system for reading image information based on light from a reading scanning surface are provided, and the writing optical system and the reading optical system have at least one common optical element. I am trying.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configurations of various embodiments of the scanning optical system according to the present invention will be described in detail below with reference to the accompanying drawings. First, the configuration of a first embodiment of a scanning optical system having two optical systems, a reading optical system R and a writing optical system W, will be described with reference to FIGS. In the scanning optical system 10 of the first embodiment, the reading optical system R and the writing optical system W have a common optical path, and the reading operation and the writing operation independent from each other can be simultaneously executed. It is configured like.

FIG. 1 is a diagram showing the arrangement of the scanning optical system 10 according to the first embodiment in the sub-scanning plane. The writing optical system W includes a collimator 12 as a writing light source unit, a cylindrical lens 14, and an objective lens 1.
6, a polygon mirror 18 as a deflection mirror, a cylindrical mirror 20 as a curved mirror, and a toric lens 22 as an anamorphic lens. The collimator 12 has a semiconductor laser 12a that outputs a modulated laser beam having a first wavelength as a writing laser beam Lw, and a collimator lens 12b that makes the writing laser beam Lw a parallel light beam. .
The cylindrical lens 14 is a lens having power only in the sub-scanning direction. The objective lens 16 has power in both the main and sub scanning directions. The deflection mirror (polygon mirror 18) reflects / deflects the incoming laser beam. The laser beam reflected and deflected by the polygon mirror 18 is reflected by a cylindrical mirror 20 having power in the main scanning direction. The toric lens 22 does not give power to the laser beam folded by the cylindrical mirror 20 in the main scanning direction but positive power only in the sub scanning direction.

The laser beam Lw for writing which has passed through the toric lens 22 is constructed so as to be converged on the surface to be scanned, that is, the surface Sw of the photosensitive layer as the writing scanning surface which is arranged on the outer periphery of the photosensitive drum PD. ing. The optical axis of the writing laser beam Lw is, as shown in the figure,
It is set so that the light is incident outside the rotation center O of the photosensitive drum PD. As a result, the surface of the photosensitive drum PD, that is,
The reflected light on the writing scanning surface Sw does not return to the incident optical path. Therefore, since the reflected light is prevented from entering the detector that detects the output level of the laser beam Lw for maintaining the output level of the writing laser beam Lw constant, the output of the laser beam Lw is prevented. Maintaining the level is surely achieved. Furthermore, this photosensitive drum P
The incident position of the laser beam Lw on D is set so that the reflected light does not return to the light receiving element 38 of the reading optical system R.

In this specification, the main scanning direction means
The deflection direction of the laser beam by the polygon mirror 18, that is, the rotation axis direction of the photosensitive drum, is the sub-scanning direction.
This is the direction orthogonal to the main scanning direction, that is, the rotation direction of the photosensitive drum.

The reading optical system R comprises a collimator 24, a cylindrical lens 26 and an objective lens 2.
8, the first beam splitter 30, the second beam splitter 32, and the polygon mirror 18, the cylindrical mirror 20, the toric lens 22, and
Third beam splitter 34, anamorphic lens 3
6, the light receiving element 38 is provided. The collimator 24 functions as a reading / scanning light source unit, and makes the semiconductor laser 24a that outputs a monotonic laser beam having the second wavelength as the reading / detecting laser beam LR and the reading / scanning laser beam LR into parallel light beams. And a collimator lens 24b for. Cylindrical lens 2
Reference numeral 6 denotes a lens having power only in the sub-scanning direction, and the objective lens 28 has power in both the main and sub-scanning directions.

The first beam splitter 30 outputs a laser beam L for reading and scanning output from the collimator 24.
The R and the scattered light Ls for reading detection reflected from the reading scanning surface SR are spatially separated. The second beam splitter 32 causes the reading / scanning laser beam LR from the collimator 24 that has passed through the first beam splitter 30 to enter the polygon mirror 18 through the same optical path as that of the writing optical system W described above. (That is, the light fluxes are combined). Further, the second beam splitter 32
The scattered light Ls for reading and detection reflected by the polygon mirror 18 is separated from the optical path common to the writing optical system W (that is, the light flux is separated).

The third beam splitter 34 separates the reading / scanning laser beam LR that has passed through the toric lens 22 from the optical path of the writing optical system W, and the scattered light Ls for reading / detection is the same as the incident optical path. Trace the optical path of. The scattered light Ls for reading and detection spatially separated from the optical path of the laser beam LR for reading and scanning by the above-mentioned first beam splitter 30 is converged by the anamorphic lens 36 and imaged on the light receiving element 38. . The anamorphic lens 36 also has the functions of a collimating lens, a cylindrical lens, and an objective lens. Therefore, instead of the cylindrical lens 26 and the objective lens 28,
It is also possible to use anamorphic lenses. Further, if the collimator lens is adjusted so as to emit the convergent light, the objective lens 28 becomes unnecessary.

As described above, in the first embodiment, the optical path between the second and third beam splitters 32 and 34 and the three optical elements of the polygon mirror 18, the cylindrical mirror 20 and the toric lens 22 are provided. The writing optical system W and the reading optical system R are common.

Immediately in front of the light receiving element 38, the scattered light L for reading detection is placed at a position conjugate with the reading scanning surface SR.
A perforated light-shielding plate 40 is provided which has an opening for passing s and blocks light beams other than the scattered light Ls and light beams emitted from other than the reading scanning surface SR (that is, stray light) from entering the light receiving element 38. Has been done. Further, as shown in FIG. 3, in the upper half of the cylindrical mirror 20, in order to prevent the surface reflected light from various optical elements from being taken in by the light receiving element 38 as stray light, flocking is performed as a stray light absorbing member. The member 42 is attached. As described above, in the first embodiment, various measures are taken against stray light, and the adverse effect such as the occurrence of ghost is prevented. Further, by arranging this opening at a position conjugate with the reading scanning plane SR, it is possible to change the light receiving position in the optical axis direction within the range where the light beam diameter enters the light receiving surface of the light receiving element 38.

Next, the individual optical elements in the configuration of the scanning optical system 10 described above will be specifically described.

The cylindrical lens 14 in the writing optical system W described above has no power in the main scanning direction, but has power only in the sub scanning direction. The objective lens 16 has power in both the main and sub scanning directions. Here, the powers of the cylindrical lens 14 and the objective lens 16 in the sub-scanning direction are such that the laser beam Lw output from the collimator 12 in the sub-scanning direction is in the main scanning direction in the vicinity of the reflecting surface of the polygon mirror 18 in the combined state. It is set so as to form a line image extending along the line image. Further, the power of the objective lens 16 in the main scanning direction is formed so that the laser beam Lw output from the collimator 12 forms an image on the back side of the writing scanning surface Sw in a state where no power is applied from the other. It is set.

In the first embodiment, the polygon mirror 18 is driven to rotate at a high speed by a polygon motor (not shown) around the rotation axis, and as shown in FIG. The surfaces are arranged so that they are located equidistant from the center of rotation. That is, in the first embodiment, each reflecting surface is set in a state in which the reflecting surfaces adjacent to each other intersect each other by 120 degrees and stand up vertically. On the other hand, the optical axis of the writing collimator 12 is such that the laser beam is oblique to the polygon mirror 18 from outside the main scanning plane (that is, at a predetermined angle in the sub-scanning direction) toward the rotation center of the polygon mirror 18. It is set so that it is incident from below.

The above-mentioned cylindrical mirror 20 is formed so as to be a spherical surface in the main scanning plane and a flat surface in the sub scanning plane. That is, it has the power to converge the laser beam folded here in the main scanning direction, and does not have the power to converge the laser beam folded here in the sub-scanning direction. The toric lens 22 is formed so as to be curved in the direction opposite to the cylindrical mirror 20 in the main scanning plane as shown in FIG. 2, and its optical axis is in the sub-scanning plane as shown in FIG. It is arranged so as to be eccentric with respect to the optical path. The toric lens 22 has no power in the main scanning direction,
The power is set to have a positive power only in the sub-scanning direction, and the power is set to increase from the periphery to the center.

Since the cylindrical mirror 20 is a flat surface in the sub-scanning plane, the laser beam folded here forms an image with a field curvature in the sub-scanning plane. Therefore, the power of the toric lens 22 in the sub scanning direction is within the depth of focus because the laser beam reflected and deflected by the polygon mirror 18 is the writing scanning surface Sw and the field curvature in the sub scanning surface is corrected. It is set to converge so that it forms an image. The power of the cylindrical mirror 20 in the main scanning direction is temporarily changed by the power of the objective lens 16 to the writing scanning surface S.
The laser beam focused so as to form an image on the back side of w is converged so as to form an image on the writing scanning surface Sw.

The laser beam reflected and deflected by the polygon mirror 18 also enters the cylindrical mirror 20 at an angle in the sub-scanning direction, is folded back by the cylindrical mirror 20, and is then toric lens 2.
The setting is toward the writing scanning surface Sw via the line 2. That is, in the first embodiment, as shown in FIG.
The optical path of the writing optical system W and various optical elements are not only arranged in a state of being wide in the main scanning plane,
It is also arranged so as to extend in the sub-scanning direction. In other words, the cylindrical mirror 20 is shown in FIG.
As shown in FIG. 5, the lens is arranged in a state parallel to the sub-scanning plane and is displaced above the cylindrical lens 14 and the objective lens 16.

The cylindrical lens 26 and the objective lens 28 constituting the reading optical system R are formed so as to have substantially the same functions as the cylindrical lens 14 and the objective lens 16 constituting the writing optical system W.

In the first embodiment, both the second and third beam splitters 32 and 34 described above selectively pass or reflect the respective laser beams LR and Lw based on the wavelengths of the incident laser beams. Is formed.
It should be noted that in the first embodiment, the synthesis / separation of laser beams is not limited to being performed based on the wavelength, but as will be described later in detail as a modification, the polarization direction of the laser beams is changed. It may be executed based on this.
Further, it may be configured so as to be executed based on the combined state, that is, the wavelength and the polarization direction.

The second and third beam splitters 32 and 34 in the first embodiment are both composed of dichroic mirrors arranged at an angle of 45 degrees with respect to the optical path, as shown in FIG. Has been done. Here, this dichroic mirror has a laser beam L having a first wavelength λ1.
The laser beam LR of the second wavelength .lambda.2 has a wavelength selecting function of allowing the laser beam L.sub.R of the second wavelength .lambda.2 to pass though w as it is.

Specifically, in the first embodiment, the first wavelength λ1 is set lower than the second wavelength λ2. As shown in FIG. 5, each of the dichroic mirrors has a first wavelength λ1 and a second wavelength λ2.
And a switching wavelength region for switching the reflectance between 0% and 100%. When the laser beam Lw having the first wavelength .lambda.1 lower than the switching wavelength region is incident on the dichroic mirror, it is allowed to pass therethrough, and the laser beam LR having the second wavelength .lambda.2 higher than the switching wavelength region is incident. And it will be possible to reflect it as it is. That is, the light beams are selectively passed or reflected according to the wavelength of the incident laser beam, and the light beams of the laser beam are combined or separated.

The optical axis of the laser beam LR emitted from the reading collimator 24 is set to be orthogonal to the optical axis of the laser beam Lw emitted from the writing collimator 12. Therefore, the laser beam (wavelength λ2) LR emitted from the reading collimator 24
Passes through the first beam splitter 30 as it is, is reflected by the second beam splitter 32, and is emitted from the collimator 12 for writing (wavelength λ1).
It advances toward the polygon mirror 18 while being combined with Lw. Then, the laser beams Lw and LR are reflected by the polygon mirror 18, and the cylindrical mirror 20.
After being folded back at, it passes through the toric lens 22. Laser beam Lw that has passed through the toric lens 22
, LR, only the writing laser beam Lw having the first wavelength λ1 is transmitted to the third beam splitter 34.
And is converged on the writing scanning surface Sw. The read scanning laser beam LR having the second wavelength λ2 is
It is reflected by the third beam splitter 34 and converged on the read scanning surface SR.

The laser beam LR which scans the reading scanning surface SR is reflected by the reading scanning surface SR and becomes scattered light, but the wavelength of this scattered light remains the second wavelength λ2.
Therefore, in the reflected scattered light, the light flux of the scattered light returning along the incident optical axis goes to the third beam splitter 34 as the scattered light Ls for reading and detection. The scattered light Ls for reading and detection is reflected by the third beam splitter 34, traces back along the same optical path as the incident optical paths of the laser beams Lw and LR to the third beam splitter 34, and reaches the polygon mirror 18. Go to The scattered light Ls for reading detection reflected by the polygon mirror 18 is
The light is reflected by the second beam splitter 32, separated from the optical path up to that point, and travels toward the collimator 24 for reading.

The first beam splitter 30 for spatially separating the reading / scanning laser beam LR output from the collimator 24 and the reading / detecting scattered light Ls reflected from the reading / scanning surface SR is As shown in FIG. 6, it is formed as a disk-shaped perforated mirror having a circular opening 30a at the center. Here, the first beam splitter 30 is arranged in a state of being inclined by 45 degrees with respect to the optical axis of the laser beam emitted from the collimator 24. Further, the opening 30a is formed so that the reading / scanning laser beam LR output from the reading collimator 24 can pass therethrough without being eclipsed. The surface of the first beam splitter 30 on the writing optical system W side is formed as a reflecting surface 30b. The size of this reflecting surface 30b is the scattered light L for reading and detection.
It is set in consideration of the sensitivity of the light receiving element 38 by determining the amount of the light flux of s 2 taken into the light receiving element 28.

As mentioned above, the second beam splitter 3
The scattered light Ls for reading and detection reflected and separated by 2 is
In the first beam splitter 30, the opening 30a
Except for the light flux passing through, the light is reflected by the reflecting surface 30b, converged by the anamorphic lens 36, and imaged by the light receiving element 38. The light receiving element 38 is configured to output a read detection signal to an image reading device (not shown) in accordance with the intensity of the read detection scattered light Ls imaged here. Here, the luminous intensity of the scattered light Ls for reading detection changes based on the black and white information on the reading scanning surface SR, and when the reflection portion of the reading laser beam LR on the reading scanning surface SR is black, reading The light intensity of the scattered light Ls for detection is low, and is high when it is white. In this way, the detection position is specified by the vertical synchronization signal and the horizontal synchronization signal (not shown) based on the read detection signal from the light receiving element 38, so that the reading scanning surface SR
The image of can be detected (recognized).

In the scanning optical system 10 of the first embodiment configured as described above, the modulated laser beam Lw output from the collimator 12 for writing is mainly controlled by the power of the cylindrical lens 14 and the objective lens 16. It is converged in both the scanning direction and the sub-scanning direction, and is incident on the second beam splitter 32. Since the laser beam Lw has the first wavelength λ1, it passes through the second beam splitter 32 as it is, and has an angle with respect to the polygon mirror 18 from outside the main scanning plane, that is, in the sub-scanning direction. , Enters toward the center of rotation of the polygon mirror 18. Here, the laser beam Lw incident on the polygon mirror 18 is more strongly converged in the sub-scanning direction by the power of the cylindrical lens 14, and as a result, in the vicinity of the reflecting surface of the polygon mirror 18, once in the main scanning direction. A line image extending along it will be formed.

The laser beam Lw reflected and deflected by the polygon mirror 18 is incident on the cylindrical mirror 20 while having an angle in the sub-scanning direction, and is returned here to the toric lens 22. Since the laser beam Lw that has passed through the toric lens 22 has the first wavelength λ1, it passes through the third beam splitter 34 as it is and heads for the writing scanning surface Sw. Here, in the main scanning direction, the laser beam Lw directed to the writing scanning surface Sw is once converged by the objective lens 16 so as to form an image on the back side of the writing scanning surface Sw, and further by the power of the cylindrical mirror 20. , Are converged so as to form an image on the writing scanning surface Sw.
Further, the laser beam Lw directed to the writing scanning surface Sw
Is the cylindrical lens 1 in the sub-scanning direction.
4, the objective lens 16 and the toric lens 22 converge the light and form an image on the writing scanning surface Sw. In this way, on the writing scanning surface Sw,
The writing operation is executed according to the modulation content of the laser beam Lw output from the collimator 12.

On the other hand, the monotone laser beam LR output from the reading collimator 24 is converged by the power of the cylindrical lens 26 and the objective lens 28 in both the main scanning direction and the sub-scanning direction, and the first beam splitter. 30 through the opening 30a. Since the laser beam LR has the second wavelength λ2, it is reflected by the second beam splitter 32 and is combined with the laser beam Lw for writing to the polygon mirror 18 and the main scanning surface. It is incident from the outside, that is, with an angle in the sub-scanning direction, toward the center of rotation of the polygon mirror 18. Here, polygon mirror 1
Similarly to the writing laser beam Lw, the reading laser beam LR incident on the laser beam 8 is more strongly converged in the sub-scanning direction by the power of the cylindrical lens 14, and as a result, in the vicinity of the reflecting surface of the polygon mirror 18. Then, a line image extending along the main scanning direction is once formed.

The laser beam LR reflected and deflected by the polygon mirror 18 is incident on the cylindrical mirror 20 while having an angle in the sub-scanning direction while being combined with the writing laser beam LW. After being turned back at, it goes toward the third beam splitter 34 through the toric lens 22. Since the laser beam LR has the second wavelength .lambda.2, it is reflected by the third beam splitter 34 toward the reading scanning surface SR and further reflected by the reading scanning surface SR, and the scattered light Ls for reading detection is detected. Becomes The scattered light Ls is reflected by the third beam splitter 34 so as to return along the same optical path as the optical path of the read laser beam LR, and the toric lens 22 again.
After passing through, it is folded back by the cylindrical mirror 20 and heads for the polygon mirror 18.

The scattered light Ls for reading and detection after being reflected by the polygon mirror 18 is the second beam splitter 3.
2 and the reflecting surface 3 of the first beam splitter 30
The reflected light is reflected by 0b, is converged by the anamorphic lens 36, and the light receiving element 38 receives the reflected light. Light receiving element 3
Based on the read detection signal from 8, the reading operation is executed.

As described in detail above, according to the scanning optical system 10 of the first embodiment, the writing operation and the reading operation can be executed in completely independent states. As a result, when the scanning optical system 10 is applied to, for example, a facsimile apparatus, the reading optical system R is used to read and scan an original for transmission, and at the same time, a received original sent through a telephone line is illustrated. An image can be formed on the recording paper by using the writing optical system W. In other words, even if a document is transmitted from another place through the telephone line while scanning and scanning the document for transmission, the received document is not stored in the memory once and is synchronized with the receiving operation. It is possible to write the received image of the lever. Another example is
A printer for a computer having an image reader function capable of inputting a read image to a computer using a reading optical system R and performing printout using a writing optical system W based on image information output from the computer. It is also possible to provide

Further, in the scanning optical system 10 in the above-mentioned first embodiment, when viewed from the sub-scanning direction, the polygon mirror 18 is seen from substantially the center of the main scanning area (however, with an angle in the sub-scanning direction). By injecting the laser beams LR and Lw toward the rotation center of the polygon mirror 18, the scannable angle range can be set larger than the size of the polygon mirror 18, so that the size of the polygon mirror 18 is kept constant. By doing so, it is possible to scan a wider range than in the past. Further, if the scanning range is fixed, the diameter of the polygon mirror 18 can be made smaller than in the conventional case. Further, since the field curvature occurs symmetrically with respect to the optical axis of the optical system, its correction becomes easy.

In the first embodiment, the laser beams LR and Lw are incident on the polygon mirror 18 at an angle in the sub-scanning direction. Therefore, as the polygon mirror 18 rotates, the direction of the line image changes according to the rotation angle, so that skew distortion occurs. When skew distortion occurs in the light beam, the laser beams LR and L
The wavefront aberration of w increases, and the convergence performance of the spot on the writing scanning surface Sw or the reading scanning surface SR is deteriorated. The skew distortion of the light beam becomes larger in the peripheral portion of the scanning range. If the scanning range is small, no substantial problem occurs without taking any measures, but if the scanning range is wide, some measures are required. In the first embodiment, since the scanning range is wide, the skew distortion of the light beam generated by the polygon mirror 18 causes the optical axis of the toric lens 22 in the sub-scanning direction with respect to the optical path as described above. It is offset by making it eccentric.

The skew distortion correction function of the toric lens 22 will be described with reference to FIG. As described above, the optical axis of the toric lens 22 is decentered with respect to the optical path in the sub scanning direction. For this reason, the light flux has a locus H different from the generatrix G of the toric lens 22 and the toric lens 2
The surface of 2 will be scanned. When passing through the toric lens 22, the light flux is not a linear shape but a predetermined elliptical shape. In FIG. 2, in order to show the directionality of the skew distortion, the light beam is represented by a thick line having a direction corresponding to the line image near the polygon mirror 18. In this way, by scanning the position away from the generatrix G and utilizing the prism effect of the toric lens 22, the skew distortion of the light flux is corrected.

Further, by decentering the optical axis of the toric lens 22 as described above, it becomes easy to prevent noise. FIG. 37 shows how the writing laser beam Lw enters the toric lens 22.
(A) shows a conventional configuration in which the optical axis of the writing laser beam Lw and the optical axis of the toric lens 22 are aligned. In this case, when a part of the incident beam is reflected by the lens surface of the toric lens 22 on the scanned surface Sw side, the reflected light returns to the beam incident side by tracing the same optical path as the incident light. The reflected light is further reflected by the lens surface of the toric lens 22 on the beam incident side, travels toward the surface to be scanned again, and is combined with the incident light to the toric lens 22 and emitted. In this way, in the conventional configuration, the beam is emitted to the surface to be scanned in the state where the original transmitted beam Lw is combined with the surface reflected light inside the lens.

On the other hand, according to the configuration of the first embodiment shown in FIG. 37B, the writing laser beam Lw that passes through the toric lens 22 and goes directly to the surface to be scanned and the surface reflected light (in the figure). (Indicated by a broken line) travels in different optical paths in the sub-scanning direction. That is, since the surface reflected light that becomes noise and the original writing laser beam Lw are emitted from the toric lens 22 in a separated state, only the noise component (surface reflected light) is blocked and the writing laser beam Lw is cut off. Light-shielding member S having a slit for passing
By providing P, it is possible to prevent the surface reflected light from reaching the surface to be scanned. The principle described here is applicable not only to the laser beam for writing but also to the reading / scanning optical system.

In the writing scanning system W of the first embodiment, the laser beam is the polygon mirror 18.
Is configured to be incident obliquely in the sub-scanning direction. The laser beam is also configured to enter the cylindrical mirror 20 obliquely in the sub-scanning direction. Therefore, BOW, which is a bend of the scanning line in the sub-scanning direction, occurs on the scanning surface. However, in this first embodiment, as will be explained below, both BOWs cancel each other out so that B is substantially
The OW does not occur on the scanning surface.

First, referring to FIG. 7, a writing scanning system W
In, the BOW that occurs when the laser beam obliquely enters the polygon mirror 18 in the sub-scanning direction will be described.

FIG. 7 shows the change of the deflection point with the rotation of the polygon mirror 18. Reference numeral 18a shows the deflection point when the laser beam is vertically incident on the reflection surface of the polygon mirror 18, and reference numeral 18a. Reference numerals 18b respectively indicate deflection points when the polygon mirror 18 is rotated by a predetermined angle in the arrow direction. Here, since the laser beam is obliquely incident on the polygon mirror 18, the deflection point in the main scanning direction changes as shown in FIG. 7A due to the rotation of the polygon mirror 18, and at the same time, in the sub scanning direction. Also changes as shown in FIG. As a result, on the reflection surface of the polygon mirror 18, a curved locus is drawn as shown in FIG. Therefore, the reflected laser beam from the polygon mirror 18 is displaced in the sub-scanning direction depending on the rotational position of the polygon mirror 18, as shown in FIG. Even if the deflection point does not change, the laser beam is obliquely incident on the polygon mirror 18,
Corresponding to the rotation of the polygon mirror 18, the locus of the reflected light has a conical shape.

The deviation of the reflected laser beam caused by these two factors, that is, the change of the deflection point and the change of the deflection direction, is enlarged or reduced by the optical system in the subsequent stage, and the BOW on the writing scanning surface Sw is increased. Will be generated.

Next, with reference to FIG. 8, the BOW generated when the laser beam obliquely enters the cylindrical mirror 20 in the sub-scanning direction will be described.

FIG. 8A shows the state of reflection in the main scanning plane, and FIG. 8B shows the state of reflection in the sub-scanning plane. The periphery of the scanning range,
The reflection points at the middle portion and the center portion are denoted by reference numerals 20a and 20 respectively.
b, 20c. These reflection points 20a, 2
0b and 20c are separated by a maximum ΔX distance along the optical axis direction. The laser beam is a cylindrical mirror 20.
Since the incident laser beams are incident obliquely as shown in FIG. 4B, the reflected laser beams La, Lb, and Lc are incident on the respective incident laser beams. The angle α formed is constant, but there is a shift in parallel with each other, which causes BOW on the writing scanning surface Sw.

In the scanning optical system 10 of the first embodiment, the polygon mirror 18 and the cylindrical mirror 20 are included.
Is configured so that the BOWs in opposite directions are generated in the respective mirrors, and the BOWs are set so as to cancel each other, so that the BOWs on the writing scanning surface Sw are
The occurrence of is substantially suppressed.

Here, in order to generate BOW at the polygon mirror 18, in the first embodiment, the laser beam is directed in the sub-scanning direction to the polygon mirror 18 having a reflecting surface parallel to the rotation axis. Although the light is incident from the outside of the main scanning surface at an angle, as another method, it is possible to use a tapered polygon mirror whose reflection surface is inclined with respect to the rotation axis.

When the laser beam is scanned on the writing scanning surface Sw using the cylindrical mirror 20, as shown in FIG.
As shown in FIG. 5, the curvature of field r of the cylindrical mirror 20, the distance D ′ from the cylindrical mirror 20 to the writing scanning surface Sw, and the scanning coefficient K change the field curvature and the fθ error. Then, the radius of curvature r and the distance D ′
Let D be the distance from the object point of the incident laser beam to the cylindrical mirror 20 along the optical axis, P be the distance between the deflection point and the cylindrical mirror 20, and f be the focal length in the main scanning plane of the scanning system. , Is calculated from the following formula. That is,

[0058]

## EQU1 ## f = (D + P) .D '/ D (1)

## EQU00002 ## 1 / D '= (1 / D) + (2 / r) (2) From equation (1),

## EQU00003 ## D '= f.D / (D + P) (3) From equations (2) and (3),

## EQU00004 ## r = 2f.D / (D + P-f) (4)

Here, in FIGS. 10 to 13, scanning coefficients K = 105, K = 125, K = 135.5, and K = 18, respectively.
At 0, the image height is 10 with the distances D and P as parameters.
It is the diagram which calculated fθ error (DELTA) y and field curvature DM in 8 mm. As is clear from these diagrams, it can be seen that there is a combination of the distances D and P that minimize the fθ error Δy and the field curvature DM at each scanning coefficient K. The scanning coefficient K is a constant K when the relationship between the deflection angle θ of the polygon mirror 18 and the image height Y is expressed by the following equation (5), and indicates a virtual focal length of the scanning optical system 10. Is.

(5) Y = Kθ (5)

On the other hand, in the reading optical system R of the first embodiment, the structure is advantageous against noise, that is, the scattered light Ls for reading detection incident on the light receiving element 38 is less likely to be ridden by noise. There is. The noise resistance performance will be described below.

In the first embodiment, the reading laser beam LR and the writing laser beam Lw output from the collimator 24 as the reading light source section are combined or separated. In doing this,
The second and third beam splitters 32 are configured by a dichroic mirror that selectively passes / reflects a light beam according to an incident wavelength without using a half mirror that reflects only half of the incident light amount and passes the other half. , 34 are configured. Further, the first beam splitter 30 is constituted by a perforated mirror that spatially separates the scattered light Ls for reading detection reflected and returned on the reading scanning surface SR from the optical path of the laser beam LR for reading scanning. is doing.

If a half mirror is used as the beam splitter, the amount of light will be halved each time the light beam passes through the half mirror, and the scattered light Ls for reading and detection will be used.
Are more susceptible to noise.

In the first embodiment, the first beam splitter 30 spatially separates the luminous flux, and the second and third beam splitters 32 and 34 are used.
Is to separate the light flux based on the wavelength. That is, the first
Through the third beam splitters 30, 32, 34, the light amount of the light flux when splitting or splitting is not substantially reduced. Further, the first beam splitter 30 is configured so that the reflected component of the reading / scanning laser beam LR does not enter the light receiving element 38.

Therefore, according to the first embodiment, it is surely prevented that the reading / scanning scattered laser beam LR will be reflected by the first beam splitter 30 as noise due to the reading / scanning scattered light Ls. Then, only the scattered light Ls for reading and detecting is incident on the light receiving element 38. In this way, the read detection signal is reliably output from the light receiving element 38 based on the image information contained in the scattered light Ls for read detection.

Further, in the first embodiment, an optical system is provided such that the fθ lens is not provided between the polygon mirror 18 and the reading scanning surface SR, but the cylindrical mirror 20 is provided as an optical element replacing the fθ lens. It constitutes the system. Therefore, the problem of surface reflection that occurs when the deflected light flux passes through the lens does not occur at all. Further, since it is set so as to be obliquely incident on the cylindrical mirror 20 at an angle in the sub-scanning direction, and is set to be incident on a position deviated from the optical axis of the toric lens 22, It is possible to reliably prevent the surface reflection component from going back up the incident light path and riding on the scattered light Ls for reading and detection as a noise component. In this way, based on the image information included in the scattered light Ls for reading and detection,
From the light receiving element 38, a read detection signal without noise is surely output.

In the first embodiment, when the scattered light Ls for reading detection reflected and returned on the reading scanning surface SR is separated from the optical path of the laser beam LR for reading scanning, they are separated from each other. Since both have the same wavelength, the beam splitter composed of the dichroic mirror described above cannot be used. In the first embodiment, in order to separate the scattered light Ls for reading and detection from the optical path of the laser beam LR for reading and scanning, the concept of spatial separation based on the difference in the spread of both light beams is introduced.
It was possible to spatially separate the two by using the beam splitter 30 of.

In the first embodiment, the light source section is described as being composed of a semiconductor laser and a collimating lens, but a gas laser capable of obtaining a substantially parallel light flux such as a He--Ne or Ar laser. May be used, and when modulation is required, a modulator may be used.

It goes without saying that the present invention is not limited to the configuration of the above-mentioned first embodiment and can be variously modified without departing from the scope of the present invention. less than,
A modification of the first embodiment and various other embodiments will be described.

A scanning optical system 10 'as a first modification of the above-described first embodiment will be described with reference to FIGS. A scanning optical system 10 'according to the first modification.
Also in (1), the reading optical system R and the writing optical system W have a common optical path, and the reading operation and the writing operation independent of each other can be simultaneously executed. In the first embodiment described above, the image could be read only as a monotone image, whereas in the first modified example, reading and writing of a color image with color resolution is possible. The configuration is different from that of the first embodiment described above.

In the following description, the same components as those described in the first embodiment will be designated by the same reference numerals and the description thereof will be omitted. In the scanning optical system 10 'according to the first modification of the first embodiment, the collimator device 44 is adopted as the writing light source, and
The collimator device 46 is also used as a light source for reading.

As shown in FIG. 15, the collimator device 44 has a red collimator 44A for outputting a red modulated laser beam having only P polarization direction to the beam splitter 32 'shown in FIG. 14, and has only P polarization direction. A green collimator 44B for outputting a green modulated laser beam, and P
A blue collimator 44C for outputting a blue modulated laser beam having only a polarization direction, and a red collimator 44A
The cylindrical lens 14 and the objective lens 16 are arranged on the optical axis of. In addition, the red collimator 44A and the cylindrical lens 14
The fourth and fifth beam splitters 48 and 50 are sequentially provided in the optical path between and along the output direction of the red laser beam, and are arranged at an angle of 45 degrees with respect to the optical path. There is.

Here, the fourth beam splitter 48 is
The fifth beam splitter 50 is configured by a dichroic mirror formed to transmit the red light flux but reflect the green light flux, and the fifth beam splitter 50 transmits the red light flux and the green light flux.
It is composed of a dichroic mirror formed so as to reflect a blue light beam. And the green collimator 44B
Are arranged so as to output a green laser beam toward the corresponding fourth beam splitter 48 along a direction orthogonal to the optical axis of the red collimator 44A. Further, the blue collimator 44C is arranged so as to output a blue laser beam toward the corresponding fifth beam splitter 50 along a direction orthogonal to the optical axis of the red collimator 44A.

Since the collimator device 44 is constructed as described above, the red collimator 44A and the green collimator 4 are
4B and the blue modulated laser beam respectively output from the blue collimator 44C are the fourth and fifth beam splitters 48 and 50.
Then, the modulated laser beams, which are sequentially combined and mixed, are output as a laser beam for writing.

The collimator device 46 as a light source for reading is basically constructed in the same manner as the collimator device 44 as a light source for writing. A red monotone laser beam having an S polarization direction, a green monotone laser beam having an S polarization direction, and a blue monotone laser beam having an S polarization direction are output from the collimator, the green collimator, and the blue collimator, respectively. . That is, in the first modification, the collimator device 44 for writing outputs a modulated laser beam having a P polarization direction,
The reading collimator device 46 is set to output a monotone laser beam having an S polarization direction.

In the first modification, as shown in FIG. 14, the second and third beam splitters 32 ', 3'
4'is configured to selectively transmit or reflect the light beam depending on the polarization direction. Each of the second and third beam splitters 32 'and 34' is composed of a glass plate having a polarization selection film on its surface.
As shown in FIG. 4, they are arranged in a state of being inclined by 45 degrees with respect to the optical path. This polarization selection film has a selectivity with respect to the polarization direction that allows a light beam having only the P polarization direction to pass therethrough and reflects a light beam having only the S polarization direction. These second and third beam splitters 32 'and 34'
When a light beam having both the P-polarization direction and the S-polarization direction is incident on, the light is transmitted and reflected in a dispersed state according to each polarization direction.

16 and 17 are views showing a prism-shaped beam splitter which can be used in place of the mirror-shaped beam splitter described above. In this case, the second and third beam splitters 32 ', 34' are shown in FIG.
As shown in FIG. 6, first and second prism glasses each having a right-angled isosceles triangular shape in cross section are provided so that their slopes are 4 ° to the optical path.
The light-incident surface and the light-exiting surface are combined so as to be orthogonal to each other, and the polarization-selective film is interposed between the respective oblique surfaces. ing. As in the case of the mirror-like beam splitter described above, this polarization selection film transmits a light beam having only P polarization direction as shown in FIG. 17 and reflects a light beam having only S polarization direction as shown in FIG. Let That is, as shown in FIG. 19, when a light beam having both the P-polarization direction and the S-polarization direction is incident, it is transmitted and reflected in a state of being dispersed according to each polarization direction.

In order to read image information corresponding to each color, the reading optical system R has a red light receiving element 52A having a red light receiving sensitivity, a green light receiving element 52B having a green light receiving sensitivity, and a blue light beam. A blue light receiving element 52C having a light receiving sensitivity is provided, the red light receiving element 52A is disposed at the image forming position of the anamorphic lens 36, and in the optical path between the red light receiving element 52A and the anamorphic lens 36, The sixth and seventh beam splitters 5 are arranged along the incident direction of the scattered light Ls for reading and detection.
4, 56 are arranged in a state of being inclined at 45 degrees with respect to the optical path.

Here, the sixth beam splitter 54 is
The dichroic mirror is configured to transmit red light and green light but reflect blue light. The seventh beam splitter 56 is formed to transmit red light but reflect green light. It consists of a dichroic mirror. The blue light receiving element 52C is arranged at a position where the blue light reflected by the corresponding sixth beam splitter 54 forms an image. In addition, the green light receiving element 52
B is arranged at a position where the green light reflected by the corresponding seventh beam splitter 56 forms an image.

In the scanning optical system 10 'according to the first modification constructed as described above, the modulated laser beam Lw having the P polarization direction output from the collimator device 44 for writing has the cylindrical lens 14 and The power of the objective lens 16 converges in both the main scanning direction and the sub-scanning direction, and since it has the P polarization direction, it passes through the second beam splitter 32 'as it is, The light enters from outside the scanning plane, that is, while having an angle in the sub-scanning direction, toward the rotation center of the polygon mirror 18. here,
The laser beam Lw incident on the polygon mirror 18 is more strongly converged in the sub-scanning direction by the power of the cylindrical lens 14, and as a result, the polygon mirror 18
A line image extending in the main scanning direction is once formed in the vicinity of the reflection surface of the.

Then, the laser beam Lw reflected and deflected by the polygon mirror 18 is reflected by the cylindrical mirror 20.
Also, the third beam splitter 34 ′ has an angle of incidence in the sub-scanning direction, is reflected at this point, passes through the toric lens 22, and has a P polarization direction.
Is transmitted as it is to the writing scanning surface Sw. Here, in the main scanning direction, the laser beam Lw directed to the writing scanning surface Sw is once converged by the objective lens 16 so as to form an image on the back side of the writing scanning surface Sw, and by the power of the cylindrical mirror 20. It is converged so as to form an image on the writing scanning surface Sw. On the other hand, the laser beam Lw directed to the writing scanning surface Sw is converged by the cylindrical lens 14, the objective lens 16, and the toric lens 22 in the sub-scanning direction, and forms an image on the writing scanning surface Sw. In this way, on the writing scanning surface Sw, the writing operation of the color image is executed according to the modulation content of each color of the laser beam Lw output from the collimator 44.

In the first modification, the photosensitive layer forming the writing scanning surface Sw has a photosensitive sensitivity for each color, in other words, a color image can be formed. Needless to say.

The monotone laser beam LR having the S polarization direction output from the image reading collimator 24 is used as the cylindrical lens 26 and the objective lens 2.
By the power of 8, the light passes through the opening 30 of the first beam splitter 30 while being converged in both the main scanning direction and the sub-scanning direction, and since it has the S polarization direction, it is reflected by the second beam splitter 32 '. The polygon mirror 1 is formed in a state where it is combined with the writing laser beam Lw.
8 is incident from the outside of the main scanning plane, that is, with an angle in the sub-scanning direction, toward the rotation center of the polygon mirror 18. Here, the reading laser beam LR incident on the polygon mirror 18 is similar to the image writing laser beam Lw, and the cylindrical lens 14
With the power of, it converges more strongly in the sub-scanning direction,
As a result, a line image extending in the main scanning direction is once formed near the reflecting surface of the polygon mirror 18.

The laser beam LR reflected and deflected by the polygon mirror 18 is incident on the cylindrical mirror 20 while having an angle in the sub-scanning direction, and after being reflected here, passes through the toric lens 22 and is S-polarized. Since it has a direction, it is reflected by the third beam splitter 34 'toward the reading scanning surface SR. The laser beam LR for reading is reflected by the reading scanning surface SR for each color to become scattered light Ls for reading detection. This scattered light Ls is reflected by the third beam splitter 34 'so as to return along the same optical path as that of the reading laser beam LR, passes through the toric lens 22 again, and is reflected by the cylindrical mirror 20. The light is reflected and deflected by the polygon mirror 18 and heads for the second beam splitter 32 '.

The scattered light Ls for reading and detection after being reflected by the polygon mirror 18 is reflected by the second beam splitter 32 'and also by the reflecting surface 30b of the first beam splitter 30. , Is converged by the anamorphic lens 36, is sequentially reflected by the sixth and seventh beam splitters 54, 56 for each color, and is imaged on the detection surface of each of the corresponding light receiving elements 52A, 52B, 52C. It will be a matter. The light receiving elements 52A, 52B for each color,
Based on the reading detection signal from 52C, the reading operation of the color image on the reading scanning surface SR is executed.

As described in detail above, according to the first modification, the reading optical system R and the writing optical system W have the common optical path, and the reading operation and the writing operation independent from each other are simultaneously executed. In addition to being able to read, a color image can be read and a color image can be written with resolution for each color. Although chromatic aberration becomes a problem when a normal color image is handled, in the first embodiment, since the reflective optical system is used in the scanning unit, the configuration is advantageous for chromatic aberration.

Next, a scanning optical system 10 ″ according to a second modification of the first embodiment of the present invention will be described with reference to FIGS.

In the second modification, the reading optical system R and the writing optical system have a common optical path so that the reading operation and the writing operation can be simultaneously executed. The beam splitter is configured not to transmit / reflect the light beam according to the wavelength but to selectively transmit / reflect the light beam according to the polarization direction. The laser beam for reading and the laser beam for writing It is equipped with a common collimator as a light source for outputting both.

That is, the scanning optical system 10 ″ according to the second modification has a common collimator 60 for reading and writing, as shown in FIG. Second beam splitter 32 in the embodiment of
The first beam splitter 62 in the second modified example is arranged corresponding to the position where the first beam splitter 62 is arranged.
The first beam splitter 30 of this embodiment is composed of a space separation type perforated mirror. Further, the second beam splitter 64 in the second modification is arranged corresponding to the position where the third beam splitter 34 of the first embodiment is arranged, which corresponds to the first beam splitter described above. Similar to the third beam splitter 34 'in the modified example,
It is configured so that transmission or reflection can be selectively switched according to the polarization direction of the incident light beam. Specifically, in the second modification, the second beam splitter 64 transmits only the P-polarization direction component (that is, the modulated laser beam Lw for writing) in the incoming laser beam. However, the S polarization direction component (that is, the monotonic laser beam LR for reading) is set to be reflected.

On the other hand, the collimator 60 is constructed so as to output a monotone laser beam having a linearly polarized component of only the S polarization direction, and the polarization / modulation device 66 is provided in the optical path between the collimator 60 and the cylindrical lens 14. Is installed. The polarization / modulation device 66 includes a collimator 60.
An element having an electric / optical effect (hereinafter, simply referred to as an E / O element) 66a disposed on the side, and a λ / 4 plate 66b disposed on the side of the cylindrical lens 14 are provided. By this E / O element 66a, the laser beam is directed to the cylindrical lens 14 in a polarization state having an arbitrary polarization angle, that is, an S ratio and a P polarization component of an arbitrary ratio. The second modification 10 ″ is configured so that only the P-polarized component of the laser beam can be output in a state where it is modulated according to image information.

The polarization control function of the polarization / modulation device 66 will be described using a well-known Poincare sphere. In Poincaré's sphere, linearly polarized light lies on the equator. The position representing the linearly polarized light of only the S-polarized component and the position representing the linearly polarized light of the P-polarized component are separated by 180 degrees on the equator.
The linear polarization state located on the equator between them represents the linear polarization state with a predetermined inclination angle (that is, having a P polarization component and an S polarization component at a predetermined ratio). The E / O element 66a is configured to be able to move the incident laser beam having only the S-polarized component at an angle corresponding to the input voltage in the latitudinal direction from the equator of the Poincare sphere. ing. In other words, it is configured so that the incident laser beam can be converted into elliptically polarized light having an arbitrary oblateness defined by an arbitrary latitude in the Poincare sphere.

Specifically, when a positive voltage of 100% of the predetermined voltage is input, it moves 180 degrees in the latitudinal direction and is positioned on the equator on the opposite side. As a result, the polarization direction of linearly polarized light is increased. Is set to be converted from the S-polarized component to the P-polarized component. When a positive voltage of 50% of the predetermined voltage is input, it moves by 90 degrees toward the North Pole and moves to the zenith (that is, the North Pole).
% Flatness, that is, converted to circularly polarized light. 2 of specified voltage
If a positive voltage of 5% is input, 4 in the north pole direction
Moving 5 degrees, this results in conversion of linearly polarized light to elliptically polarized light with an oblateness of 45%.

Further, the λ / 4 plate 66b indicates the polarization state of the laser beam incident on the λ / 4 plate 66b at a position on the equator where linear polarization of only S-polarized component and a position of linear polarization of only P-polarized component are shown. It has a function of rotating the position indicating the polarization state on the equator by rotating it by 90 degrees around the diameter connecting with. As a result, when the laser beam passes through the λ / 4 plate 66b, the elliptically polarized light set by the E / O element 66a becomes
It will be converted into a linearly polarized state having a predetermined inclination angle corresponding to the flatness of this. That is, the E / O element 66a
The image information is represented by the angle of inclination of the linearly polarized light by changing the voltage input to the signal according to the image information.

More specifically, as shown in FIG. 21, when the light intensity of the P-polarized component is plotted on the horizontal axis and the light intensity of the S-polarized component is plotted on the vertical axis, the laser output from the polarization / modulation device 66. The light intensity of the beam will be represented as a vector. In the example of FIG. 21, the E / O element 66 at the time point a in the course of time elapses from a → b → c → d → e.
A positive voltage of 50% of the predetermined voltage, a positive voltage of 100% at the time point b, a positive voltage of 66% at the time point c, a positive voltage of 38% at the time point d, and a 33% voltage at the time point e. Positive voltages are sequentially input to the E / O element 66a. In this case, the oblateness converted into elliptically polarized light is 90% at the time point a (that is, circularly polarized light), and b
180% at the time (that is, linearly polarized light of S-polarized component only)
, 120% at time c, 70% at time d, and 60% at time e.

A laser beam having such an oblateness is
It is converted into linearly polarized light by passing through the λ / 4 plate 66b. As shown in FIG. 21, the inclination angle θ is θ at the time point a.
a = 45 degrees, θb = 90 degrees at time point b, θc = 6 at time point c
0 degrees, θd = 35 degrees at time d, and θd = 3 at time e
It becomes 0 degree, and is converted into a linearly polarized state, which is expressed as a vector having a P-polarization direction component and an S-polarization component corresponding to each θ angle, and is output.

In FIG. 21, the absolute length of each vector showing the linear polarization state shows the light intensity of the light flux.
This is defined by the light intensity of the laser beam output from the collimator 60. In this second modification, as shown in FIG. 21, the light intensity of the laser beam output from the collimator 60 is set so that the light intensity of the S-polarized component at each time point becomes constant. As a result, the temporal change in the light intensity of the S polarization direction component of the laser beam output from the polarization / modulation device 66 becomes constant as shown in FIG. 22, and the temporal change in the light intensity of the P polarization direction component is
As shown in FIG. 23, it changes according to the image information,
Therefore, the light intensity of the P polarization direction component is modulated according to the image information.

In this way, the polarization / modulation device 66 outputs a laser beam in which the P-polarized component is modulated according to the image information and the S-polarized component is monotonous. That is, in the second modification, the polarization / modulation device 6
The writing operation is executed based on the P-polarized component of the laser beam output from the laser beam 6, and the reading operation is executed based on the S-polarized component.

In the scanning optical system 10 ″ according to the second modified example having the above-described configuration, the monotonic laser beam output from the collimator 60 is converted into image information by the polarization / modulation device 66 only for the P-polarized component. Modulated accordingly,
The S-polarized component remains monotonic and enters the cylindrical lens 14. The laser beam converged in both the main scanning direction and the sub-scanning direction by the power of the cylindrical lens 14 and the objective lens 16 passes through the aperture of the perforated mirror as the first beam splitter 62 as it is, and is directed to the polygon mirror 18. Then, the light enters from the outside of the main scanning plane, that is, while having an angle in the sub-scanning direction, toward the center of rotation of the polygon mirror 18. Here, the writing and reading laser beams Lw and LR incident on the polygon mirror 18 are strongly converged in the sub-scanning direction by the power of the cylindrical lens 14, and once near the reflection surface of the polygon mirror 18, A line image extending in the main scanning direction is formed.

The laser beams Lw and LR reflected and deflected by the polygon mirror 18 also enter the cylindrical mirror 20 with an angle in the sub-scanning direction, and after being reflected here, pass through the toric lens 22 to reach the first position. 2 towards the beam splitter 64. The laser beam Lw of the P-polarized component passes through the second beam splitter 64 as it is, and becomes the scanning surface Sw as the writing laser beam Lw.
Will be heading to.

Here, the laser beams Lw and LR that have passed through the toric lens 22 are temporarily scanned by the objective lens 16 in the scanning plane Sw in the main scanning direction.
, SR to form an image on the back side, and the power of the cylindrical mirror 20 to form an image on the writing scanning surface Sw. On the other hand, the laser beams Lw and LR that have passed through the toric lens 22 are converged by the powers of the cylindrical lens 14, the objective lens 16 and the toric lens 22 in the sub-scanning direction, and are imaged on the scanning surfaces Sw and SR. Will be In this way, on the writing scanning surface Sw, the image writing operation is executed according to the modulation content of the laser beam Lw of the P-polarized component in the laser beam output from the polarization / modulation device 66. become.

On the other hand, the laser beam L having the S-polarized component in the laser beam transmitted through the toric lens 22.
R is reflected by the second beam splitter 64 and travels toward the reading scanning surface SR as the reading laser beam LR. The reading laser beam LR is reflected by the reading scanning surface SR to become scattered light Ls for reading detection. This scattered light Ls is a laser beam L for both writing and reading by the second beam splitter 64.
The light is reflected back along the same optical path as w and LR, passes through the toric lens 22, is returned by the cylindrical mirror 20, is reflected and deflected by the polygon mirror 18, and is directed to the first beam splitter 62. Scattered light Ls for reading detection after being reflected by the polygon mirror 18.
Is reflected by the first beam splitter 62, converged by the anamorphic lens 36, and imaged on the detection surface of the light receiving element 38. In this way, the reading operation of the image on the reading scanning surface SR is executed based on the reading detection signal from the light receiving element 38.

As described in detail above, according to the second modification, the reading optical system R and the writing optical system W have a common optical path, and the reading operation and the writing operation independent of each other are simultaneously executed. In addition to being able to do so, only one collimator is required as a laser light source, and space saving can be achieved.

In the structure of the second modified example described above, as shown in FIGS. 21 and 22, the collimator 60 is
The light intensity of the laser beam (that is, the absolute length of the vector shown in FIG. 21) so that the S polarization direction component is always constant.
Is set to change and output. However, the present invention is not limited to such a configuration, for example,
The S-polarization direction component is not constant, and specifically, the S-polarization direction component may be output so that the S-polarization direction component is different at the time points corresponding to both end portions and the central portion of the scanning range.

In the first modified example and the second modified example of the first embodiment, the optical axis of the toric lens 22 is decentered with respect to the optical path, as in the first embodiment. Is.

Next, the configuration of the second embodiment of the scanning optical system according to the present invention will be described in detail with reference to FIG.
In the second embodiment, similar to the first embodiment described above, the writing optical system W and the reading optical system R have a common optical path, but switching for switching the writing function and the reading function. As a result, unlike the first embodiment, a writing function and a reading function are selectively executed.

The scanning optical system 70 according to the second embodiment.
24 has a collimator 72 commonly used for reading and writing, as shown in FIG. The collimator 72 is configured to be capable of outputting a laser beam modulated according to image information and also capable of outputting a monotonic laser beam in a switched state. Further, the beam splitter 74 in the second embodiment is arranged corresponding to the position where the second beam splitter 32 in the first embodiment is arranged. The beam splitter 74 is composed of a space separation type perforated mirror similar to the first beam splitter 30 of the first embodiment. In addition, in the optical path between the cylindrical mirror 20 and the toric lens 22,
A movable reflection mirror 76 is provided as a switching means.

In the second embodiment, the movable reflecting mirror 76 is not shown between the writing position retracted from the optical path and the reading position set to cross the optical path at an inclination angle of 45 degrees. It is configured to be movable by a drive source. At the time of writing, the collimator 72 outputs the laser beam Lw modulated according to the image information while the movable reflecting mirror 76 is moved to the writing position. The modulated laser beam Lw folded back by the cylindrical mirror 20 is converged by the toric lens 22 and imaged on the writing scanning surface Sw. On the other hand, at the time of reading, the movable reflecting mirror 76 is moved to the reading position, and the collimator 72 outputs the monotone laser beam LR. The monotone laser beam LR folded back by the cylindrical mirror 20 is reflected by the movable reflecting mirror 76, converged by another toric lens 78, imaged on the reading scanning surface SR, and reflected there. ing.

In the scanning optical system 70 according to the second embodiment configured as described above, the writing mode or the reading mode is selectively set by the writing / reading changeover switch (not shown). When the writing mode is set, the movable reflecting mirror 76 is moved to the writing position, and the modulated laser beam Lw is emitted from the collimator 72.
Is output. The modulated laser beam Lw is converged in both the main scanning direction and the sub scanning direction by the power of the cylindrical lens 14 and the objective lens 16, passes through the aperture of the perforated mirror as the beam splitter 74, and is directed to the polygon mirror 18. The light enters from the outside of the main scanning plane, that is, while having an angle in the sub-scanning direction, toward the center of rotation of the polygon mirror 18. here,
Since the laser beam Lw incident on the polygon mirror 18 is more strongly converged in the sub scanning direction by the power of the cylindrical lens 14, a line image extending in the main scanning direction is once formed near the reflecting surface of the polygon mirror 18. Will be done.

The laser beam Lw reflected and deflected by the polygon mirror 18 also enters the cylindrical mirror 20 with an angle in the sub-scanning direction, is folded back here, and is then moved to the movable reflecting mirror 76 at the writing position. , The toric lens 22, and the writing scanning surface Sw is scanned. In this way, on the writing scanning surface Sw, the image writing operation is executed according to the modulation content of the laser beam Lw output from the collimator 72.

On the other hand, when the reading mode is set, the movable reflecting mirror 76 is moved to the reading position and the collimator 72 outputs the monotone laser beam LR.

In this case, since the movable reflecting mirror 76 is at the reading position, the monotonic laser beam LR is reflected by the movable reflecting mirror 76 and goes through the toric lens 78 toward the reading scanning surface SR. The reading laser beam LR is reflected by the reading scanning surface SR and becomes scattered light Ls for reading detection. This scattered light Ls is
The movable reflection mirror 76 reflects the laser beam LR for reading so as to return along the same optical path as the incident optical path, and is reflected by the cylindrical lens 20, and then is reflected by the polygon mirror 18.
It is reflected and deflected by and is directed to the beam splitter 74.

The reading scattered light Ls is reflected by the beam splitter 74, converged by the anamorphic lens 36, and imaged on the detection surface of the light receiving element 38. Based on the read detection signal from the light receiving element 38, the image reading operation on the reading scanning surface SR is executed.

As described in detail above, according to the second embodiment, the reading optical system R and the writing optical system W have a common optical path, and the optical elements such as the polygon mirror 18 and the cylindrical mirror 20 are provided. By making common use, the configuration can be simplified, and the overall configuration can be downsized and the cost can be reduced.

The above-mentioned writing / reading changeover switch may be configured to be manually changed by the operator, and, for example, in a facsimile machine, when the original transmission mode is selected, the original mode is automatically changed over to the reading mode. Can be switched to an image forming mode automatically when received via a telephone line, and can be switched by an electric signal or software.

In the second embodiment and the modification of the second embodiment to be described later, the optical axis of the toric lens 22 is arranged eccentrically with respect to the optical path as in the first embodiment. Has been done.

Next, the second scanning optical system according to the present invention will be described.
A first modification of the embodiment will be described with reference to FIGS. 25 and 26. The scanning optical system 70 'according to the first modification is provided with a switching means for switching between the writing function and the reading function in a mode different from that of the second embodiment. Also, in the scanning optical system 70 ', unlike the above-described first embodiment, an fθ lens is provided as an optical element that replaces the cylindrical mirror 20.

As shown in FIG. 25, the scanning optical system 70 'according to the first modification of the second embodiment is constructed as a writing optical system W in the same manner as in the second embodiment described above.
A collimator 72 that outputs a laser beam having a P polarization direction to the beam splitter 84, a cylindrical lens 14, a polygon mirror 18, and a laser beam reflected and deflected by the polygon mirror 18 on the writing scanning surface Sw. The fθ lens 80 is formed so as to perform scanning at a uniform linear motion and to form a laser beam on the writing scanning surface Sw at any incident angle to the writing scanning surface Sw. Has been done.

On the other hand, the reading optical system R is provided with the λ / 2 plate 82, which is provided in the structure of the writing optical system W described above, so as to be movable back and forth with respect to the optical path between the collimator 72 and the cylindrical lens 14 described above. , Fθ lens 80 and the beam splitter 8 in the optical path between the writing scanning surface Sw.
4, a cylindrical lens 86, a fluorescent fiber 88, and a pair of light receiving elements 90a and 90b. λ /
The two-plate 82 changes the polarization direction of the transmitted light beam, that is, emits the laser beam having the P-polarization direction incident on it as a laser beam having the S-polarization direction. In the beam splitter 84, the polarization direction of the incident light beam is P
When the polarization direction is S, the light is transmitted, and when the S polarization direction is, the light is reflected. The cylindrical lens 86 converges the scattered light Ls for reading detection as the reflected light reflected by the reading scanning surface SR, and the scattered light Ls converged by the cylindrical lens 86.
Is imaged on the fluorescent fiber 88. The light amount of the scattered light Ls thus formed is detected by the pair of light receiving elements 90a and 90b arranged at both ends of the fluorescent fiber 88.

Here, the cylindrical lens 86 is composed of a Fresnel lens, and is arranged in the state of extending in the scanning direction near the irradiation position of the laser beam on the reading scanning surface SR. In addition, the fluorescent fiber 88
Is also arranged so as to extend along the scanning direction, emits fluorescence by an incident light flux, guides it in the extending direction, and emits light from both ends. Therefore, this fluorescent fiber 8
A pair of light receiving elements 90a and 90b arranged at both ends of
Will detect the amount of light emitted by the fluorescent fiber 88 at both ends in response to the received light. A pair of light receiving elements 90a, 9
0b is connected to an image reading device (not shown), and an image is read based on the absolute intensity of light emitted from each device.

The movable λ / 2 plate 82 described above can be moved by a drive source (not shown) between a writing position retracted from the optical path and a reading position located in the optical path. At the time of writing, the collimator 72 outputs the laser beam Lw modulated according to the image information while the movable λ / 2 plate 82 is moved to the writing position. The laser beam Lw is reflected and deflected by the polygon mirror 18,
It is converged by the fθ lens 80, and an image is formed on the writing scanning surface Sw. On the other hand, at the time of reading, the movable λ / 2 plate 82 is moved to the image reading position, and the collimator 72 outputs the monotone laser beam LR. The monotonic laser beam LR has its polarization direction changed to the S polarization direction by the movable λ / 2 plate 82, is then reflected and deflected by the polygon mirror 18, is converged by the fθ lens 80, is reflected by the beam splitter 84, and is for writing. The laser beam is separated from the optical path of the laser beam and is imaged on the reading scanning surface SR, where it is reflected.

As described above, even if the fθ lens 80 is used without using the cylindrical mirror, the same effect as that of the second embodiment can be obtained. Moreover, by separating the light beams according to the polarization direction of the light beams, the optical path in the writing optical system W and the optical path in the reading optical system R can be shared.

Next, a second modification of the second embodiment of the scanning optical system according to the present invention will be described with reference to FIG. Incidentally, the scanning optical system 70 ″ according to the second modification is provided with a beam splitter 74 and a movable reflecting mirror 76 for spatially separating a light beam, as in the second embodiment.
Moreover, a configuration is adopted in which the fθ lens 80 is provided without using a cylindrical mirror.

In the scanning optical system 70 ″ according to the second modification, the writing mode or the reading mode is selectively set by a writing / reading switch not shown. When the writing mode is set, the movable reflection The mirror 76 is brought to the writing position as in the second embodiment, and the modulated laser beam L is emitted from the collimator 72.
w is output. The modulated laser beam Lw is converged by the power of the cylindrical lens 14, passes through the aperture of the perforated mirror as the beam splitter 74,
The light enters the polygon mirror 18 toward the center of rotation of the polygon mirror 18 in the main scanning plane. The laser beam Lw incident on the polygon mirror 18 is emitted by the cylindrical lens 1
With the power of 4, the light converges more strongly in the sub-scanning direction, and a line image extending in the main-scanning direction is once formed near the reflecting surface of the polygon mirror 18.

The laser beam Lw reflected and deflected by the polygon mirror 18 is converged by the fθ lens 80, passes the side of the movable reflecting mirror 76 at the writing position, and is scanned by the writing scanning surface Sw. Become. In this way, on the writing scanning surface Sw, the image writing operation is executed according to the modulation content of the laser beam Lw output from the collimator 72.

On the other hand, when the reading mode is set, the movable reflecting mirror 76 is brought to the reading position as in the second embodiment, and the monotonous laser beam L is emitted from the collimator 72.
R is output. This monotonic laser beam LR is converged by the power of the cylindrical lens 14, passes through the aperture of the perforated mirror as the beam splitter 74,
The light enters the polygon mirror 18 in the main scanning plane toward the rotation center thereof.

The laser beam LR reflected and deflected by the polygon mirror 18 is converged by the fθ lens 80, reflected by the movable reflection mirror 76 at the reading position, and directed to the reading scanning surface SR. The reading laser beam LR is reflected by the reading scanning surface SR and becomes scattered light Ls for reading detection. This scattered light L
s is reflected by the movable reflection mirror 76 so as to return along the same optical path as the incident optical path of the reading laser beam LR, and fθ
After passing through the lens 80, it is reflected by the polygon mirror 18,
It is deflected and goes to the beam splitter 74.

The scattered light Ls for reading detection after being reflected by the polygon mirror 18 is the beam splitter 74.
Is reflected by and is converged by the anamorphic lens 36,
An image is formed on the detection surface of the light receiving element 38. Based on the read detection signal from the light receiving element 38, the image reading operation on the reading scanning surface SR is executed.

As described above, also in the second modified example using the fθ lens 80 in place of the cylindrical mirror, it is possible to achieve the same effect as that of the second embodiment described above. Also in this case, as in the second embodiment, the light beam can be spatially separated by the beam splitter 76 composed of a perforated mirror, so that the optical path in the writing optical system W and the optical path in the reading optical system R are separated. Can be shared.

Next, the construction of the third embodiment of the scanning optical system according to the present invention will be described in detail with reference to FIG.

In the third embodiment, unlike the above-mentioned first and second embodiments, the writing optical system W and the reading optical system R each have an independent optical path, and are relatively used as optical elements. The expensive polygon mirror 18 is provided as an element common to both optical systems. Further, similarly to the first embodiment and its modification, the writing process and the reading process independent from each other can be simultaneously executed.

Scanning optical system 100 according to the third embodiment.
28 is provided with a reading optical system R and a writing optical system W which are independently arranged with the polygon mirror 18 as a boundary, as shown in the arrangement in the sub-scanning plane in FIG.

The writing optical system W includes a collimator 12, a cylindrical lens 14, and an objective lens 1.
6, cylindrical mirror 20, toric lens 22
Have. The collimator 12 outputs a laser beam modulated based on image information as a writing laser beam Lw. The cylindrical lens 14 is a lens having power only in the sub-scanning direction, and the objective lens 16 is a lens having power in both the main and sub-scanning directions. The laser beam Lw reflected by the polygon mirror 18 is reflected by the cylindrical mirror 20 having power only in the main scanning direction.
The laser beam Lw folded back by the cylindrical mirror 20 is incident on the toric lens 22 as an anamorphic lens having no power in the main scanning direction and positive power only in the sub scanning direction.

The reading optical system R includes a collimator 24, a cylindrical lens 26, and an objective lens 2.
8, beam splitter 30, cylindrical mirror 10
4, a toric lens 106, a reflection mirror 108, an anamorphic lens 36, and a light receiving element 38.

The collimator 24 outputs the monotone laser beam as a laser beam LR for reading and detection. The cylindrical lens 26 is a lens having power only in the sub-scanning direction, and the objective lens 28 is
This lens has power in both the main and sub scanning directions. The beam splitter 30 spatially separates the reading / scanning laser beam LR output from the collimator 24 and the reading / detecting scattered light Ls reflected from the reading / scanning surface SR. The cylindrical mirror 104 turns the laser beam LR reflected and deflected by the polygon mirror 18 by giving power only in the main scanning direction. The laser beam LR folded by the cylindrical mirror 104 does not give power in the main scanning direction, but gives positive power only in the sub-scanning direction, and the toric lens 106 as an anamorphic lens.
And is reflected by the reflection mirror 108 toward the surface to be scanned SR. The anamorphic lens 36 is a lens for converging the scattered light Ls for reading and detection spatially separated from the optical path of the laser beam LR for reading and scanning by the beam splitter 30 described above. The scattered light Ls for detection converged by the anamorphic lens 36 forms an image on the light receiving element 38. The toric lens 22
The toric lens 106 is arranged with its optical axis decentered with respect to the optical path, as in the first embodiment.

In the third embodiment, the polygon mirror 18 is provided with a writing optical system W and a reading optical system R by setting the reflection position of the polygon mirror 18 to be different from that for reading. It is arranged to be commonly used.

In the scanning optical system 100 of the third embodiment constructed as described above, the collimator 12 for writing is used.
The modulated laser beam Lw output from the optical system is converged by the power of the cylindrical lens 14 and the objective lens 16 in both the main scanning direction and the sub-scanning direction, and is directed to the polygon mirror 18 from outside the main scanning plane, that is, The light enters toward the center of rotation of the polygon mirror 18 while having an angle in the sub-scanning direction. here,
The laser beam Lw incident on the polygon mirror 18 is more strongly converged in the sub-scanning direction by the power of the cylindrical lens 14 and once forms a line image extending in the main scanning direction near the reflecting surface of the polygon mirror 18. It will be a matter.

The laser beam Lw reflected and deflected by the polygon mirror 18 is incident on the cylindrical mirror 20 while having an angle in the sub-scanning direction, and after being reflected here, passes through the toric lens 22 to write. Head toward the scan plane Sw. With respect to the main scanning direction, the laser beam Lw directed to the writing scanning surface Sw is once converged by the objective lens 16 so as to form an image on the back side of the writing scanning surface Sw, and by the power of the cylindrical mirror 20, the writing scanning surface Sw. It will be converged so as to form an image on Sw. On the other hand, in the sub-scanning direction, the cylindrical lens 14, the objective lens 16,
Then, it is converged by the toric lens 22, reflected by the reflection mirror 102, and imaged on the writing scanning surface Sw. In this way, the writing operation is executed on the writing scanning surface Sw according to the modulation content of the laser beam Lw output from the collimator 12.

On the other hand, the monotonic laser beam LR output from the reading collimator 24 is converged by the powers of the cylindrical lens 26 and the objective lens 28 in both the main scanning direction and the sub scanning direction, and the aperture of the beam splitter 30. After passing through 30a, the light enters the polygon mirror 18 from outside the main scanning plane, that is, while having an angle in the sub-scanning direction, toward the rotation center of the polygon mirror 18. Here, the reading laser beam LR incident on the polygon mirror 18 is more strongly converged in the sub-scanning direction by the power of the cylindrical lens 14, and as a result, the polygon mirror 18
A line image extending in the main scanning direction is once formed in the vicinity of the reflection surface of the.

The laser beam LR is reflected by the polygon mirror 18
The writing laser beam Lw is reflected and deflected at a position different from the position where it is reflected and deflected, and is incident on the cylindrical mirror 104 with an angle in the sub-scanning direction. After passing through the lens 106, at the reflection mirror 108, the reading scanning surface SR
Is reflected toward. Laser beam LR for reading
Is reflected by the reading scanning surface SR to become scattered light Ls for reading and detection. The scattered light Ls follows the same optical path as that of the reading laser beam LR and reaches the first beam splitter 30. Considering the cross section of the light beam at the position of the beam splitter 30, the scattered light Ls occupies a larger area than the laser beam LR. Therefore, if the size of the aperture 30a of the perforated mirror as the first beam splitter 30 is made sufficiently small within the range where the laser beam LR passing therethrough cannot be blocked, the scattered light Ls is reflected by the reflector 30b. Then, the light is converged by the anamorphic lens 36 and travels to the light receiving unit 38. Moreover, it is possible to freely set the amount of light incident on the light receiving element 38 by changing the size, shape (curvature), etc. of the reflecting portion 30b.

As described in detail above, according to the scanning optical system 100 of the third embodiment, the writing operation and the image reading operation can be simultaneously executed in completely independent states. Further, since the polygon mirror, which is a relatively expensive optical element, can be shared by the writing optical system W and the reading optical system R, cost reduction can be achieved.

Next, the structure of the scanning optical system 100 'according to the first modification of the above-mentioned third embodiment will be described with reference to FIGS. In the first modification, the writing optical system W is configured by using the fθ lens 80, and in the reading optical system R, the scattered light Ls for reading and detecting traces the incident optical path of the laser beam LR for reading and scanning. Without receiving the light receiving element 38 via the condenser lens 110.
It is configured to be guided upward.

As shown in the first modification, the writing optical system W in the third embodiment can employ the fθ lens 80 without using the cylindrical mirror 20. In the reading optical system R, the scattered light Ls for reading and detection is directly guided onto the light receiving element 38 via the condenser lens 110 without returning the incident optical path of the laser beam LR for reading and scanning. It can also be done. In this way, in the first modification, the beam splitter 30 composed of the perforated mirror can be omitted from the configuration of the third embodiment, so that cost reduction can be achieved. Become. Since the reading resolution is determined by the laser beam LR, the condenser lens 110 that guides the light to the light receiving element 38 may be simple.

Next, the configuration of the scanning optical system 100 ″ according to the second modification of the above-described third embodiment will be described with reference to FIGS. 31 and 32. In the second modification, The writing optical system W includes the cylindrical mirror 20, and the reading optical system R includes the fθ lens 80. Here, the fθ lens 80 is configured to have telecentricity. In the reading optical system R, the peak direction of the scattered light Ls for reading and detection is perpendicular to the reading scanning surface SR in the main scanning cross section, and in order to take it in, it is formed on the light receiving element 38 via the condenser lens 112. It is designed to be imaged.

As shown in the second modification, the configuration of the reading optical system R in the third embodiment is not limited to the use of the cylindrical mirror 20, and fθ
An optical system using the lens 80 can also be adopted, and in the reading optical system R, the scattered light Ls for reading and detecting is not returned to the incident optical path of the laser beam LR for reading and scanning. Has become. In addition, since the fθ lens 80 has telecentricity, by directly condensing it on the light receiving element 38 via the condensing lens 112, a uniform amount of light can be obtained within the scanning range and regular reflection is possible. It is also possible to read a document containing many components.

Here, in the second modification described above,
Although the fθ lens 80 has been described as being configured to have telecentricity, the present invention is not limited to this, and FIG.
Also, as shown in FIG. 34, an optical system may be configured using a non-telecentric fθ lens 80. in this case,
The condenser lens 112 'is arranged so as to cover a wider range than the scanning range, and uses an anamorphic Fresnel lens. According to this structure, it is not necessary to use an expensive fθ lens having a telecentric property, and the cost can be reduced.

For the purpose of cost reduction, fθ
When the lens 80 is configured to have non-telecentricity, as shown in FIGS. 35 and 36, after the scattered light Ls for reading and detection is converged by the curved mirror 114 and is deflected, it is reflected by the reflecting mirror 116. The light may be folded back so as to pass through the fθ lens 80, and the scattered light Ls that is transmitted through the fθ lens 80 and converged may be condensed on the light receiving element 38. Even with such a configuration, the telecentric f
As compared with the case where the θ lens is provided, the optical system can be constructed at a lower cost.

In the modification of the third embodiment shown in FIGS. 33 and 35, the writing optical system W is configured to include the cylindrical mirror 20, but the present invention is not limited to this, and an fθ lens is used. It goes without saying that it may be configured as an optical system.

FIG. 38 shows the scanning optical system 20 of the fourth embodiment.
0 is shown. In the scanning optical system 200, the writing optical system W has substantially the same configuration as that of the first embodiment. However, the scanning optical system 20 of the fourth embodiment
At 0, there is no structure for irradiating the reading laser beam, and the light source 21 is provided near the reading scanning surface SR.
0 is provided. The light source 210 is a reading scanning surface S
It irradiates R 1 with incoherent light that continuously has light of a plurality of wavelengths. In the fourth embodiment, as a light source 210 for irradiating light having a continuous spectral distribution in the visible region, a fluorescent tube 201 extending in the main scanning direction and an axial direction of the fluorescent tube extending along the fluorescent tube are provided. The reflective plate 202 is provided. The writing laser beam Lw is configured to emit a laser beam having a wavelength λ1 longer than any of the plurality of wavelengths included in the light emitted from the fluorescent tube 201. Further, both the second beam splitter 32 ″ and the third beam splitter 34 ″ are configured by dichroic mirrors that transmit light having a wavelength λ1 and reflect light having a wavelength in the visible region.

In the scanning optical system 200 of the fourth embodiment constructed as described above, the collimator 12 for writing is used.
The modulated laser beam Lw output from the laser beam Lw is converged by the powers of the cylindrical lens 14 and the objective lens 16 in both the main scanning direction and the sub-scanning direction, and is incident on the second beam splitter 32 ″. , Having the first wavelength λ1 is transmitted through the second beam splitter 32 ″ as it is, and the polygon mirror 18 is angled from outside the main scanning plane, that is, in the sub-scanning direction. It is incident toward the center of rotation of 18.

The laser beam Lw reflected and deflected by the polygon mirror 18 also enters the cylindrical mirror 20 with an angle in the sub-scanning direction, is reflected here, and travels toward the toric lens 22. Since the laser beam Lw that has passed through the toric lens 22 has the first wavelength λ1, it passes through the third beam splitter 34 as it is and heads for the writing scanning surface Sw. In this way, the writing operation is executed on the writing scanning surface Sw according to the modulation content of the laser beam Lw output from the collimator 12.

On the other hand, the light in the visible region emitted by the light source 210 is reflected and scattered by the reading scanning surface SR to become scattered light Ls for reading and detection. This scattered light Ls is
It is reflected by the third beam splitter 34 ″ so as to return along the same optical path as the optical path of the writing laser beam Lw, passes through the toric lens 22, is returned by the cylindrical mirror 20, and then is reflected and deflected by the polygon mirror 18. To the second beam splitter 32 ″.

The scattered light Ls for reading and detection after being reflected by the polygon mirror 18 is light containing a plurality of wavelengths in the visible region, is reflected by the second beam splitter 32 ″, and is separated from the optical path up to that point. Then, the light is converged by the anamorphic lens 36 and an image is formed on the detection surface of the light receiving element 38. In this way, the reading operation is executed based on the read detection signal from the light receiving element 38.

As described in detail above, according to the scanning optical system 200 of the fourth embodiment, the writing operation and the reading operation can be executed in completely independent states.
Moreover, since the reading scanning surface SR is not irradiated with a laser beam having a single wavelength but is irradiated with light having a plurality of wavelengths in the visible region, it is possible to avoid the phenomenon that an image of a specific color cannot be read. it can. In the scanning optical system 200, particularly in the reading optical system R, the use of an optical element composed of a lens and a prism that causes chromatic aberration is avoided and an optical element mainly composed of a reflecting surface is used. Even if one having a plurality of wavelengths is adopted, the image information to be read will not be affected in any way.

Further, the light source 210 for irradiating the surface to be scanned SR with the light having a plurality of wavelength components adopted in the above-mentioned fourth embodiment can be appropriately adopted in the above-mentioned embodiment and its modification. It is possible. That is, the reading optical system of the second embodiment or the reading optical system of the third embodiment can be replaced with the reading optical system adopted in the fourth embodiment.

[0154]

As described above, according to the present invention,
To provide a scanning optical system that includes both a reading optical system and a writing optical system, and has both common optical paths and optical elements, but is capable of simultaneously performing independent reading and writing scanning. Become.

Further, according to the present invention, both reading scanning and writing scanning can be executed, and moreover, the optical path and the optical parts are made common in the reading optical system and the writing optical system, so that the space is saved. In addition, a scanning optical system that can reduce the cost can be provided.

Further, according to the present invention, there is provided a scanning optical system capable of easily removing the noise due to the surface reflection of the optical element arranged in the optical path.

It is also possible to provide a scanning optical system in which noise generated in the reading optical system and the writing optical system does not affect the other optical system.

Further, the beam path for scanning the reading scanning surface and the reflected light reflected by the reading scanning surface are made to have a common optical path, and a beam splitter for spatially separating them is used, which contributes to space saving. At the same time, it is possible to provide a scanning optical system capable of separating the combined light flux without attenuating the light quantity.

[Brief description of drawings]

FIG. 1 is a front view schematically showing a configuration of an embodiment of a scanning optical system according to the present invention in an arrangement state in a sub-scanning plane.

FIG. 2 is a perspective view schematically showing the surface shape of the toric lens shown in FIG.

3 is a perspective view showing a state in which a writing optical system of the scanning optical system shown in FIG. 1 is taken out.

FIG. 4 is a diagram for explaining the wavelength selectivity of dichroic mirrors that form second and third beam splitters.

5 is a diagram showing wavelength characteristics with respect to reflectance of the dichroic mirror shown in FIG.

FIG. 6 is a perspective view showing the configuration of a perforated mirror that constitutes the first beam splitter.

FIG. 7 is a diagram showing generation of BOW by a polygon mirror.

FIG. 8 is a diagram showing generation of BOW by a cylindrical mirror.

FIG. 9 is a diagram for explaining factors that determine the fθ characteristic and the field curvature in the main scanning plane.

FIG. 10 is a diagram showing a correlation between fθ error and field curvature with respect to distances D and P at a scanning coefficient K = 105.

FIG. 11 is a diagram showing a correlation between fθ error and field curvature with respect to distances D and P at a scanning coefficient K = 125.

FIG. 12 shows the distances D and P at the scanning coefficient K = 135.5.
7 is a diagram showing a correlation between fθ error and field curvature with respect to FIG.

FIG. 13 is a diagram showing a correlation between fθ error and field curvature with respect to distances D and P at a scanning coefficient K = 180.

FIG. 14 is a front view schematically showing a configuration of a scanning optical system according to a first modification of the first embodiment of the present invention in an arrangement state in the sub-scanning plane.

FIG. 15 is a front view specifically showing the configuration of the collimator device shown in FIG.

FIG. 16 is a perspective view for explaining a separated state of a light beam according to a polarization direction used in the first modified example.

FIG. 17 is a perspective view showing a transmission state of a light beam having a P polarization direction by the second and third beam splitters in the first modified example.

FIG. 18 is a perspective view showing a reflection state of a light beam having an S polarization direction by the second and third beam splitters in the first modified example.

FIG. 19 is a perspective view showing a separated state of a light beam having both P and S polarization directions by the second and third beam splitters in the first modified example.

FIG. 20 is a front view schematically showing a configuration of a scanning optical system according to a second modification of the first embodiment of the present invention in an arrangement state in the sub-scanning plane.

21 is a diagram showing the light intensity levels of the S-polarization direction component and the P-polarization direction component of the laser beam output from the polarization / modulation device shown in FIG.

FIG. 22 is a diagram showing how the S-polarization direction component of the laser beam output from the polarization / modulation device changes with time.

FIG. 23 is a diagram showing how the P-polarization direction component of the laser beam output from the polarization / modulation device changes with time.

FIG. 24 is a front view schematically showing a configuration of a second embodiment of the scanning optical system according to the present invention in an arrangement state in the sub-scanning plane.

FIG. 25 is a front view schematically showing a configuration of a scanning optical system according to a first modification of the second embodiment of the present invention in an arrangement state in the main scanning plane.

FIG. 26 is a front view schematically showing a configuration of a scanning optical system according to a first modification of the second embodiment shown in FIG. 25 in an arrangement state in the sub-scanning plane.

FIG. 27 is a front view schematically showing a configuration of a scanning optical system according to a second modification of the second embodiment of the present invention in an arrangement state in the main scanning plane.

FIG. 28 is a front view schematically showing the configuration of the third embodiment of the scanning optical system according to the present invention in the arrangement state in the sub-scanning plane.

FIG. 29 is a front view schematically showing a configuration of a scanning optical system according to a first modification of the third embodiment of the present invention in an arrangement state in the sub-scanning plane.

FIG. 30 is a front view schematically showing the configuration of the scanning optical system according to the first modification of the third embodiment shown in FIG. 29 in the arrangement state in the main scanning plane.

FIG. 31 is a front view schematically showing a configuration of a scanning optical system according to a second modification of the third embodiment of the present invention in an arrangement state in the sub-scanning plane.

32 is a front view schematically showing the configuration of the reading optical system of the scanning optical system according to the second modification of the third embodiment shown in FIG. 31, and showing the arrangement in the main scanning plane. is there.

FIG. 33 is a front view schematically showing a configuration of a scanning optical system according to another aspect of the second modification of the third embodiment of the present invention in an arrangement state in the sub-scanning plane.

34 is a schematic view of the configuration of the reading optical system of the scanning optical system according to another aspect of the second modification of the third embodiment shown in FIG. It is a front view shown.

FIG. 35 is a front view schematically showing a configuration of a scanning optical system according to another aspect of the second modification of the third embodiment of the present invention in an arrangement state in the sub-scanning plane.

FIG. 36 is a schematic view of the configuration of the reading optical system of the scanning optical system according to another aspect of the second modification of the third embodiment shown in FIG. It is a front view shown.

FIG. 37 is a side view schematically showing an arrangement state of surface reflection and a light shielding member in the toric lens.

FIG. 38 is a front view schematically showing the configuration of the fourth example of the scanning optical system according to the present invention in an arrangement state in the sub-scanning plane.

[Explanation of symbols]

D Distance from the object point of incident light along the optical axis to the cylindrical mirror D'Distance from the cylindrical mirror to the scanning plane DM Field curvature f Focal length in the main scanning plane of the scanning optical system G Generatrix H Locus K Scan coefficient Ls Scattered light for reading detection LR Laser beam for reading detection Lw Writing laser beam O Center of rotation of photosensitive drum P Distance between deflection point and cylindrical mirror PD Photosensitive drum R Reading optical system r Radius of curvature of cylindrical mirror S Scan Surface SR Reading / scanning surface Sw Writing / scanning surface SP Light-shielding member W Writing optical system ΔX distance Δy fθ error 10 (10 ′; 10 ″) Scanning optical system (first embodiment) 12 Writing collimator 12a First wavelength λ1 Semiconductor laser that outputs a laser beam 12b Collimator lens 14 Cylindrical 16 Objective lens 18 Polygon mirror 20 Cylindrical mirror 22 Toric lens 24 Reading collimator 24a Semiconductor laser that outputs a laser beam of the second wavelength λ2 24b Collimator lens 26 Cylindrical lens 28 Objective lens 30 Perforated mirror 30a Opening 30b Reflecting surface 32 1st beam splitter 34 2nd beam splitter 36 Anamorphic lens 38 Light receiving element 40 Hole light-shielding plate 42 Flocking member 44 Writing collimator device 44A Red collimator 44B Green collimator 44C Blue collimator 46 Reading collimator device 48 Fourth Beam splitter 50 Fifth beam splitter 52A Red light receiving element 52B Green light receiving element 52C Blue light receiving element 54 Sixth beam splitter 56 Seventh beam splitter 60 Collimator 62 First beam splitter 64 Second beam splitter 66 Polarization / modulation device 66a E / O element 66b λ / 4 plate 70 (70 ′; 70 ″) Optical scanning System (second embodiment) 72 Collimator 74 Beam splitter 76 Movable reflection mirror 78 Toric lens 80 fθ lens 82 Movable λ / 2 plate 84 Beam splitter 86 Cylindrical lens 88 Fluorescent fiber 90a; 90b Light receiving element 100 (100 ′; 100 ″) ) Scanning optical system (third embodiment) 102 Cylindrical mirror 104 Toric lens 106 Reflecting mirror 108 Reflecting mirror 110 Imaging mirror 112 (112 ') Condensing lens 114 Curved mirror 116 Reflecting mirror. 200 Scanning Optical System (Fourth Embodiment) 210 Light Source 201 Fluorescent Tube 202 Reflector

Claims (76)

[Claims] 1. A writing optical system for scanning a writing scanning surface with a light beam modulated according to writing information, and a writing optical system for writing an image on the scanning surface, and a reading scanning surface with a light beam for reading the same. A scanning optical system comprising: a reading optical system for reading image information based on light reflected from a scanning surface, wherein the optical paths of the writing optical system and the reading optical system and at least one optical element are made common. system. 2. The scanning optical system according to claim 1, wherein the common optical element includes a deflecting mirror that reflects and deflects a light beam. 3. The common optical element has a curvature in a main scanning direction, and makes a light beam reflected and deflected by the deflection mirror have an angle in a sub-scanning direction with respect to an incident light beam on a scanning surface. Characterized by having a curved mirror that folds back to the side,
The scanning optical system according to claim 2. 4. The writing optical system includes a writing light source that outputs a laser light flux modulated according to the writing information, and the reading optical system reads and scans image information on the reading scanning surface. The scanning optical system according to claim 1, further comprising a reading light source that outputs a laser beam. 5. The scanning optical system according to claim 4, wherein the writing light source and the reading light source are each configured to output a monochromatic laser beam. 6. The writing light source is configured to output a laser light flux having writing information for each color, and the reading light source is configured to output a laser light flux having a plurality of wavelengths. The scanning surface has an image forming photosensitivity for each color and is configured to form a color image, and the reading optical system separates the reflected light from the reading scanning surface for each color, and receives the light for each color. The scanning optical system according to claim 4, further comprising a plurality of light receiving sensors. 7. The reading optical system is configured so that the reflected light from the reading scanning surface returns to the optical path of the laser beam for reading, and the reflected light is spatially separated from the laser beam for reading. 5. The scanning optical system according to claim 4, further comprising a first beam splitter that 8. The reading optical system reads from the second beam splitter for combining the writing laser beam and the reading laser beam, and the combined writing and reading laser beams. 5. The scanning optical system according to claim 4, further comprising a third beam splitter for separating a laser light beam for use in a laser beam. 9. The writing light source outputs a laser light beam having a first wavelength characteristic, and the reading light source outputs a laser light beam having a second wavelength characteristic different from the first wavelength characteristic, 9. The scanning optical system according to claim 8, wherein the second and third beam splitters selectively transmit or reflect the laser light flux according to the wavelength characteristics of the laser light flux. 10. The second and third beam splitters transmit the laser light flux having the first wavelength characteristic when the laser light flux has the first wavelength characteristic, and allow the laser light flux having the second wavelength characteristic to enter. 10. The scanning optical system according to claim 9, wherein the scanning optical system reflects the light when it occurs. 11. The writing light source outputs a laser light flux having a first polarization direction, and the reading light source outputs a laser light flux having a second polarization direction different from the first polarization direction, 9. The scanning optical system according to claim 8, wherein the second and third beam splitters selectively transmit or reflect the light beam according to the polarization direction of the light beam. 12. The second and third beam splitters transmit the laser light flux having the first polarization direction when the laser light flux has entered, and allow the laser light flux having the second polarization direction to enter. 12. The scanning optical system according to claim 11, wherein the scanning optical system reflects the light when it is reflected. 13. The shared optical element comprises a laser light source for simultaneously outputting a laser beam for reading and a laser beam for writing.
The scanning optical system described in 1. 14. The laser light source outputs a laser beam having a first polarization direction and a laser beam outputted from the light source, and outputs an output level corresponding to image information with respect to the second polarization direction. 14. The scanning optical system according to claim 13, further comprising a modulating unit that modulates the output so as to output. 15. The reading optical system is configured so that the reflected light from the reading scanning surface returns to the optical path of the laser beam for reading, and spatially separates the reflected light from the laser beam for reading. 15. The scanning optical system according to claim 14, further comprising a first beam splitter. 16. The reading optical system includes a second beam splitter for separating a laser beam for reading from a laser beam for writing and a laser beam for reading, which are simultaneously output, and the second beam splitter includes: The scanning optical system according to claim 15, wherein the light flux is selectively transmitted or reflected according to the polarization direction of the light flux. 17. The second beam splitter reflects the laser light flux having the first polarization direction when the laser light flux is incident, and reflects the laser light flux having the second polarization direction when the laser light flux is incident. The scanning optical system according to claim 16, which transmits the light. 18. A writing optical system for writing an image by scanning a writing scanning surface with a light beam which is modulated according to writing information, and a reading scanning surface which is scanned with the light beam and reflected light from this scanning surface. A reading optical system for reading image information, the writing optical system and the reading optical system are commonly provided in a switchable state, and at least one optical element is commonly provided in both optical systems. A scanning optical system characterized by being equipped. 19. The scanning optical system according to claim 18, wherein the common optical element includes a deflection mirror that reflects and deflects a light beam. 20. The common optical element has a curvature at least in the main scanning direction, and makes the light beam deflected by the deflection mirror have an angle in the sub-scanning direction with respect to the incident light beam on the scanning surface side. 20. The scanning optical system according to claim 19, further comprising a curved mirror that is folded back to the side. 21. The common optical element is a light source for selectively outputting a laser light beam modulated according to the writing information and a laser light beam for reading and scanning image information on the reading scanning surface. The scanning optical system according to claim 19, further comprising: 22. An optical path switching means is provided in the optical path, and the optical path switching means causes a writing laser beam to enter the writing scanning surface and a reading laser beam to enter the reading scanning surface. 22. The scanning optical system according to claim 21, wherein the scanning optical system is movable to and from a reading position. 23. The optical path switching means is moved to the writing position when the writing laser beam is output from the light source, and is moved to the reading position when the reading laser beam is output from the light source. The scanning optical system according to claim 22, wherein the scanning optical system is moved. 24. The light source outputs a laser light beam having a first polarization direction, and a writing laser light beam and a reading laser light beam are provided in the common optical path between the light source and the deflection mirror. When one of the two is output, the polarization direction is not changed, and when the other is output, polarization switching means for changing the polarization direction to the second polarization direction is provided. A beam splitter that transmits a laser light beam having a first polarization direction and reflects a laser light beam having a second polarization direction is provided in the common optical path with respect to the surface. The scanning optical system according to claim 21. 25. The common optical element scans the laser light flux reflected and deflected by the deflection mirror with a uniform linear motion on a scanning surface, and at any incident angle. The scanning optical system according to claim 19, further comprising an fθ lens that forms an image of the light flux on the scanning surface. 26. The reading optical system comprises a light receiving sensor for receiving the reflected light reflected by the reading scanning surface through an anamorphic lens on an optical path different from the optical path of the reading laser beam. 19. The scanning optical system according to claim 18, wherein: 27. At the sub-scanning imaging position of the anamorphic lens, a fluorescent fiber that emits fluorescence by the light incident from the side surface and guides the fluorescence in the end direction is disposed, and at both ends of this fluorescent fiber, The scanning optical system according to claim 26, wherein each of the light receiving sensors is provided. 28. The reading optical system is configured so that the reflected light from the reading scanning surface returns to the optical path of the laser beam for reading, and spatially separates the reflected light from the laser beam for reading. The scanning optical system according to claim 18, further comprising a beam splitter. 29. A writing optical system for scanning a writing scanning surface with a light beam modulated according to image information, and a writing optical system for writing an image on the scanning surface, and a scanning scanning surface with a light beam for scanning. A reading optical system for reading image information on the basis of light reflected from a surface, and an optical path of the writing optical system and an optical path of the reading optical system are independent from each other, and at least one optical element is provided. A scanning optical system that is equipped in common with an optical system. 30. The scanning optical system according to claim 29, wherein the common optical element includes a deflection mirror for reflecting and deflecting a light beam. 31. The writing optical system includes a writing light source that outputs a laser light flux modulated according to the writing information, and the reading optical system reads and scans image information on the reading scanning surface. The scanning optical system according to claim 30, further comprising a reading light source that outputs a laser beam. 32. The laser light flux output from the writing light source is reflected on one side of the deflection mirror, and the laser light flux output from the reading light source is reflected on the other side of the deflection mirror. 4. The method according to claim 3,
1. The scanning optical system described in 1. 33. The writing optical system has a curvature in at least a main scanning direction, and makes a laser light beam reflected and deflected on one side of the deflection mirror have an angle in a sub-scanning direction with respect to an incident light beam. 31. The scanning optical system according to claim 30, further comprising a curved mirror that is turned back to the scanning surface side. 34. The writing optical system scans a laser light flux reflected and deflected on one side of the deflecting mirror with a uniform linear motion on a scanning surface, and at any incident angle. 31. The scanning optical system according to claim 30, further comprising an f? Lens that forms an image of the light flux on the scanning surface. 35. The reading optical system has a curvature in at least a main scanning direction, and makes a laser light beam reflected and deflected on the other side of the deflection mirror have an angle in a sub-scanning direction with respect to an incident light beam. 31. The scanning optical system according to claim 30, further comprising a curved mirror that is turned back to the scanning surface side. 36. The reading optical system scans a laser beam reflected and deflected on the other side of the deflecting mirror with a uniform linear motion on a scanning surface, and at any incident angle. 31. The scanning optical system according to claim 30, further comprising an f? Lens that forms an image of the light flux on the scanning surface. 37. Surface-reflected light generated when a light beam for scanning the reading scanning surface is reflected by the surface of an optical element placed in the optical path of the reading optical system, and the optical element without being reflected by the surface. 30. The scanning optical system according to claim 1, 20 or 29, wherein the optical element is arranged so that a light beam that scans the reading scanning surface that passes through the optical path travels in a different optical path. 38. Surface-reflected light generated when a light beam for scanning the writing scanning surface is reflected by the surface of an optical element placed in the optical path of the writing optical system, and the optical element without being reflected by the surface. 30. The scanning optical system according to claim 1, 20 or 29, wherein the optical element is arranged such that a light beam that scans the writing scanning surface that passes through the optical path travels a different optical path. 39. A writing optical system for scanning a writing scanning surface with a light beam modulated according to writing information and writing an image on the scanning surface, and a reading scanning surface irradiated with light having a plurality of wavelengths. And a reading optical system for reading image information based on the reflected light from the scanning surface by illuminating with a light source for scanning the position corresponding to the light receiving element. A scanning optical system having an optical path and at least one optical element in common. 40. A writing optical system for scanning a writing scanning surface with a light beam modulated according to writing information and writing an image on the scanning surface, and irradiating the reading scanning surface with light having a plurality of wavelengths. And a reading optical system for reading image information based on the reflected light from the scanning surface by illuminating with a light source for scanning the position corresponding to the light receiving element. A scanning optical system characterized in that the optical paths are commonly provided in a switchable state, and at least one optical element is commonly provided in both optical systems. 41. A writing optical system for scanning a writing scanning surface with a light beam modulated according to writing information and writing an image on the scanning surface, and a reading scanning surface irradiated with light having a plurality of wavelengths. And a reading optical system for scanning the position corresponding to the light receiving element and reading image information based on the reflected light from the scanning surface. The optical path of the writing optical system and the reading optical system are provided. A scanning optical system characterized in that the optical path of the system is provided independently of each other, and at least one optical element is provided commonly to both optical systems. 42. Surface-reflected light generated when a light beam scanning the writing scanning surface is reflected by the surface of an optical element placed in the optical path of the writing optical system, and the optical element without being reflected by the surface. 42. The scanning optical system according to claim 37 or 41, wherein the optical element is arranged such that a light beam that scans the writing scanning surface that passes through the optical path travels a different optical path. 43. A light source for irradiating a light beam, and a light beam output from the light source for scanning the light beam on a reading scanning surface, and deflecting the reflected light from the reading scanning surface toward the light source. A deflection unit; and a beam splitter disposed in an optical path between the light source and the deflection unit and spatially separating the light flux output from the light source and the reflected light. Scanning optical system. 44. The scanning optical system according to claim 43, further comprising a light receiving means for receiving the reflected light separated by the beam splitter. 45. The beam splitter has a mirror provided with a light transmitting portion for passing a light beam output from the light source and a reflecting portion for reflecting the reflected light. Item 43 or the scanning optical system of item 44. 46. The beam splitter according to claim 43, further comprising a mirror provided with a light transmitting portion for passing the laser beam for reading and a reflecting portion for reflecting the reflected light. Or 44 scanning optics. 47. A light source for irradiating a light beam, a deflection means for deflecting the light beam output from the light source for scanning the light beam on a reading scanning surface, and a light receiving means for receiving the reflected light from the reading scanning surface. And disposed between the reading scanning surface and the light receiving means,
A lens for converging the reflected light, so that the optical axis of the light beam incident on the reading scanning surface and the optical axis of the light receiving system are different in the direction perpendicular to the scanning direction of the light beam incident on the reading scanning surface. A scanning optical system, wherein the lens and the light receiving element are arranged. 48. A writing optical system for scanning a writing scanning surface with a light beam modulated according to the writing information and writing an image on the scanning surface; and image information based on the light from the reading scanning surface. A reading optical system for reading, wherein the writing optical system and the reading optical system are at least 1
A scanning optical system having two common optical elements. 49. The writing optical system includes a writing laser light source that outputs a writing laser light flux modulated according to the writing information, and the reading optical system is a reading light source for illuminating the reading surface. 5. The method according to claim 4, further comprising:
8 scanning optics. 50. The scanning optical system according to claim 48, wherein the reading light source includes a reading laser light source for outputting a reading laser light beam. 51. A combining means for combining the writing laser light flux and the reading laser light flux, and a separating means for separating the combined writing laser light flux and the reading laser light flux. 51. The scanning optical system of claim 50. 52. The writing laser light flux and the reading laser light flux have different wavelengths, and the synthesizing means and the separating means selectively emit light fluxes in accordance with the wavelength of the incident light flux. The scanning optical system according to claim 51, further comprising a beam splitter having wavelength selectivity for transmitting or reflecting. 53. The writing laser light flux and the reading laser light flux are light fluxes having different polarization directions, and the synthesizing means and the separating means are selectively light fluxes in accordance with the polarization directions of the incident light fluxes. 52. The scanning optical system according to claim 51, further comprising a beam splitter having a polarization selectivity for transmitting or reflecting light. 54. The scanning optical system according to claim 49, wherein said light source for reading outputs light including light of a plurality of wavelengths. 55. The scanning optical system according to claim 54, wherein said light source for reading has a fluorescent tube. 56. The scanning optical system according to claim 54, wherein said light source for reading has a laser light source for combining and outputting a plurality of laser light fluxes having different wavelengths. 57. The writing optical system includes a writing light source that outputs a writing light beam modulated according to the writing information, and the reading optical system outputs a reading light beam for illuminating the reading surface. A light source for reading, wherein the at least one common optical element has only one deflection mirror that deflects the writing light beam and the reading light beam. 48 scanning optics. 58. The optical element between the deflection mirror and the writing scanning surface in the writing optical system and the optical element between the deflection mirror and the reading scanning surface in the reading optical system, 58. The scanning optical system according to claim 57, which is an optical element common to an optical system and the reading optical system. 59. The scanning optical system according to claim 58, wherein said common optical element has an fθ lens. 60. The scanning optical system according to claim 58, wherein the common optical element has a curved mirror having a function of an fθ lens. 61. The scanning optical system according to claim 60, wherein the common optical element comprises an anamorphic lens between the curved mirror and the writing scanning surface. 62. The scanning optical system according to claim 61, wherein an optical axis of the anamorphic lens is decentered with respect to an optical axis of the scanning optical system. 63. The scanning optical system according to claim 60, 61 or 62, wherein said curved mirror has a non-reflective surface with a stray light absorbing member for absorbing stray light. 64. The scanning optical system according to claim 48, wherein the writing optical system and the reading optical system have a common laser light source. 65. The common laser light source is capable of outputting a laser light beam modulated based on the writing information for writing and a monotonic laser light beam for reading. Claim 64.
Scanning optics. 66. An optical path switching means for switching an optical path of a laser beam emitted from the common laser light source depending on whether writing is performed or reading is performed. Scanning optics. 67. Polarization direction switching means for switching the polarization direction of the laser light beam output from the common laser light source to a different direction depending on whether writing is performed or reading is performed, and polarization of the incident light beam. 66. The scanning optical system according to claim 65, further comprising a beam splitter that switches an optical path according to a direction. 68. The scanning optical system according to claim 64, further comprising a modulation means for modulating the laser light flux output from said common laser light source only for a predetermined polarization direction component based on said writing information. system. 69. A scanning optical system according to claim 68, further comprising a light beam separating means for separating a writing light beam and a reading light beam which are incident in a combined state. 70. The scanning optical system according to claim 69, wherein said light beam splitting means comprises a beam splitter having polarization selectivity for splitting a light beam for each polarization direction. 71. The scanning optical system according to claim 48, wherein the reading optical system includes a sensor for receiving light from the reading scanning surface. 72. The reading optical system includes a reading light source that outputs a light beam for illuminating the reading scanning surface, an optical path from the reading light source to the reading scanning surface, and the reading scanning surface to the sensor. 8. An optical path part common to the optical paths up to.
1. Scanning optical system. 73. An optical path separating means is provided which is disposed in the common optical path portion and separates the light from the reading scanning surface from the common optical path portion and advances toward the sensor. The scanning optical system according to claim 72. 74. The optical path separating means is provided with a mirror having a translucent portion for transmitting a light beam traveling from the light source to the reading surface and a reflecting portion for reflecting light from the reading surface. The scanning optical system according to claim 73. 75. The scanning optical system according to claim 74, further comprising a lens disposed in an optical path between the reading scanning surface and the sensor, the lens converging light from the reading scanning surface. 76. In the reading optical system, a light-shielding plate that is arranged between the sensor and the lens at a position conjugate with the reading scanning surface and shields light other than light from the reading scanning surface. 8. The method according to claim 7, further comprising:
5 scanning optics.